[RISC-V] Use auipc for all code addresses #116780

tomeksowi · 2025-06-18T10:21:21Z

Make all code segment addresses (for jumps, branches, data-constants, labels, etc) PC-relative.

Since the code size is limited to about 2 Gb ¹, a canonical auipc + I-type instruction combo with 32-bit range should reach anywhere. Treating code addresses as absolute even if known at compile-time is counter-effective because RISC-V needed to emit "myriad sequences" (more instructions) to synthesize long constants. It also simplifies the emitter.

Part of #84834, cc @dotnet/samsung

See this discussion. If we ever hit such failures, either the absolute addressing paths can be brought back, or some other solution like branch islands can be worked out. Either way, code sizes >2 Gb aren't likely, assuming them as default complicates the output asm. ↩

dotnet-policy-service · 2025-06-18T10:22:09Z

Tagging subscribers to this area: @JulieLeeMSFT, @jakobbotsch
See info in area-owners.md if you want to be subscribed.

risc-vv · 2025-06-18T10:26:04Z

RISC-V Release-CLR-VF2: 9084 / 9114 (99.67%)

=======================
      passed: 9084
      failed: 2
     skipped: 599
      killed: 28
------------------------
 TOTAL tests: 9713
VIRTUAL time: 11h 2min 1s 64ms
   REAL time: 45min 14s 333ms
=======================

report.xml, report.md, failures.xml, testclr_details.tar.zst

RISC-V Release-CLR-QEMU: 9083 / 9113 (99.67%)

=======================
      passed: 9083
      failed: 2
     skipped: 599
      killed: 28
------------------------
 TOTAL tests: 9712
VIRTUAL time: 35h 16min 47s 966ms
   REAL time: 36min 5s 33ms
=======================

report.xml, report.md, failures.xml, testclr_details.tar.zst

RISC-V Release-FX-VF2: 306856 / 308579 (99.44%)

=======================
      passed: 306856
      failed: 1712
     skipped: 39
      killed: 11
------------------------
 TOTAL tests: 308618
VIRTUAL time: 20h 44min 50s 168ms
   REAL time: 2h 10min 49s 664ms
=======================

report.xml, report.md, failures.xml, testclr_details.tar.zst

RISC-V Release-FX-QEMU: 274559 / 275631 (99.61%)

=======================
      passed: 274559
      failed: 1064
     skipped: 39
      killed: 8
------------------------
 TOTAL tests: 275670
VIRTUAL time: 31h 41min 43s 491ms
   REAL time: 1h 11min 0s 282ms
=======================

report.xml, report.md, failures.xml, testclr_details.tar.zst

Build information and commands

GIT: fc376f2208cbc3c3ec10b4803756ef452a83527c
CI: 3679e38be10e43c36a92b0f56774af3dfa4facf2
REPO: tomeksowi/runtime
BRANCH: emit-auipc
CONFIG: Release
LIB_CONFIG: Release

tomeksowi · 2025-06-18T10:51:57Z

No regressions. Diffs on bigger corpus coming soon.

Diffs are based on 12,289 contexts (10,113 MinOpts, 2,176 FullOpts).

Overall (-9,576 bytes)

Collection	Base size (bytes)	Diff size (bytes)	PerfScore in Diffs
test.mch	6,320,024	-9,576	-0.50%

MinOpts (-6,616 bytes)

Collection	Base size (bytes)	Diff size (bytes)	PerfScore in Diffs
test.mch	4,850,460	-6,616	-0.43%

FullOpts (-2,960 bytes)

Collection	Base size (bytes)	Diff size (bytes)	PerfScore in Diffs
test.mch	1,469,564	-2,960	-0.64%

Example diffs

test.mch

-12 (-9.68%) : 9004.dasm - Microsoft.CodeAnalysis.CSharp.Syntax.InternalSyntax.BinaryExpressionSyntax:GetSlot(int):Microsoft.CodeAnalysis.GreenNode:this (Tier1)

@@ -28,19 +28,16 @@ G_M16219_IG02:        ; bbWeight=1, gcrefRegs=0400 {a0}, byrefRegs=0000 {}, byre
             addi           ra, zero, 0xD1FFAB1E
             bltu           ra, t6, G_M16219_IG07
             zext.w         a1, a1
-            auipc          t6, 0xD1FFAB1E
-            addi           a2, t6, 0xD1FFAB1E
+            auipc          a2, 0xD1FFAB1E
+            addi           a2, a2, 0xD1FFAB1E
             slli           a3, a1, 2
             add            a2, a2, a3
             lw             a2, 0xD1FFAB1E(a2)
-            lui            t6, 0xD1FFAB1E
-            addi           t6, t6, 0xD1FFAB1E
-            lui            a3, 0xD1FFAB1E
-            slli           a3, a3, 20
-            add            a3, a3, t6
+            auipc          a3, 0xD1FFAB1E
+            addi           a3, a3, 0xD1FFAB1E
             add            a2, a2, a3
             jr             a2
-						;; size=64 bbWeight=1 PerfScore 19.00
+						;; size=52 bbWeight=1 PerfScore 14.00
 G_M16219_IG03:        ; bbWeight=0.50, gcrefRegs=0400 {a0}, byrefRegs=0000 {}, byref
             ld             a0, 0xD1FFAB1E(a0)
 						;; size=4 bbWeight=0.50 PerfScore 1.00
@@ -68,7 +65,7 @@ RWD00  	dd	G_M16219_IG03 - G_M16219_IG02
        	dd	G_M16219_IG05 - G_M16219_IG02
 
 
-; Total bytes of code 124, prolog size 16, PerfScore 38.25, instruction count 26, allocated bytes for code 124 (MethodHash=9308c0a4) for method Microsoft.CodeAnalysis.CSharp.Syntax.InternalSyntax.BinaryExpressionSyntax:GetSlot(int):Microsoft.CodeAnalysis.GreenNode:this (Tier1)
+; Total bytes of code 112, prolog size 16, PerfScore 33.25, instruction count 26, allocated bytes for code 112 (MethodHash=9308c0a4) for method Microsoft.CodeAnalysis.CSharp.Syntax.InternalSyntax.BinaryExpressionSyntax:GetSlot(int):Microsoft.CodeAnalysis.GreenNode:this (Tier1)
 ; ============================================================
 
 Unwind Info:
@@ -79,7 +76,7 @@ Unwind Info:
   E bit             : 0
   X bit             : 0
   Vers              : 0
-  Function Length   : 31 (0x0001f) Actual length = 124 (0x00007c)
+  Function Length   : 28 (0x0001c) Actual length = 112 (0x000070)
   ---- Epilog scopes ----
   ---- Scope 0
   Epilog Start Offset        : 3523193630 (0xd1ffab1e) Actual offset = 3523193630 (0xd1ffab1e) Offset from main function begin = 3523193630 (0xd1ffab1e)

-12 (-9.09%) : 9477.dasm - Microsoft.CodeAnalysis.CSharp.Syntax.InternalSyntax.BlockSyntax:GetSlot(int):Microsoft.CodeAnalysis.GreenNode:this (Tier1)

@@ -28,19 +28,16 @@ G_M31535_IG02:        ; bbWeight=1, gcrefRegs=0400 {a0}, byrefRegs=0000 {}, byre
             addi           ra, zero, 0xD1FFAB1E
             bltu           ra, t6, G_M31535_IG08
             zext.w         a1, a1
-            auipc          t6, 0xD1FFAB1E
-            addi           a2, t6, 0xD1FFAB1E
+            auipc          a2, 0xD1FFAB1E
+            addi           a2, a2, 0xD1FFAB1E
             slli           a3, a1, 2
             add            a2, a2, a3
             lw             a2, 0xD1FFAB1E(a2)
-            lui            t6, 0xD1FFAB1E
-            addi           t6, t6, 0xD1FFAB1E
-            lui            a3, 0xD1FFAB1E
-            slli           a3, a3, 20
-            add            a3, a3, t6
+            auipc          a3, 0xD1FFAB1E
+            addi           a3, a3, 0xD1FFAB1E
             add            a2, a2, a3
             jr             a2
-						;; size=64 bbWeight=1 PerfScore 19.00
+						;; size=52 bbWeight=1 PerfScore 14.00
 G_M31535_IG03:        ; bbWeight=0.56, gcrefRegs=0400 {a0}, byrefRegs=0000 {}, byref
             ld             a0, 0xD1FFAB1E(a0)
 						;; size=4 bbWeight=0.56 PerfScore 1.11
@@ -73,7 +70,7 @@ RWD00  	dd	G_M31535_IG03 - G_M31535_IG02
        	dd	G_M31535_IG05 - G_M31535_IG02
 
 
-; Total bytes of code 132, prolog size 16, PerfScore 38.17, instruction count 28, allocated bytes for code 132 (MethodHash=959684d0) for method Microsoft.CodeAnalysis.CSharp.Syntax.InternalSyntax.BlockSyntax:GetSlot(int):Microsoft.CodeAnalysis.GreenNode:this (Tier1)
+; Total bytes of code 120, prolog size 16, PerfScore 33.17, instruction count 28, allocated bytes for code 120 (MethodHash=959684d0) for method Microsoft.CodeAnalysis.CSharp.Syntax.InternalSyntax.BlockSyntax:GetSlot(int):Microsoft.CodeAnalysis.GreenNode:this (Tier1)
 ; ============================================================
 
 Unwind Info:
@@ -84,7 +81,7 @@ Unwind Info:
   E bit             : 0
   X bit             : 0
   Vers              : 0
-  Function Length   : 33 (0x00021) Actual length = 132 (0x000084)
+  Function Length   : 30 (0x0001e) Actual length = 120 (0x000078)
   ---- Epilog scopes ----
   ---- Scope 0
   Epilog Start Offset        : 3523193630 (0xd1ffab1e) Actual offset = 3523193630 (0xd1ffab1e) Offset from main function begin = 3523193630 (0xd1ffab1e)

-12 (-8.57%) : 1988.dasm - Microsoft.CodeAnalysis.CSharp.Syntax.InternalSyntax.CompilationUnitSyntax:GetSlot(int):Microsoft.CodeAnalysis.GreenNode:this (Tier1)

@@ -28,19 +28,16 @@ G_M20649_IG02:        ; bbWeight=1, gcrefRegs=0400 {a0}, byrefRegs=0000 {}, byre
             addi           ra, zero, 0xD1FFAB1E
             bltu           ra, t6, G_M20649_IG09
             zext.w         a1, a1
-            auipc          t6, 0xD1FFAB1E
-            addi           a2, t6, 0xD1FFAB1E
+            auipc          a2, 0xD1FFAB1E
+            addi           a2, a2, 0xD1FFAB1E
             slli           a3, a1, 2
             add            a2, a2, a3
             lw             a2, 0xD1FFAB1E(a2)
-            lui            t6, 0xD1FFAB1E
-            addi           t6, t6, 0xD1FFAB1E
-            lui            a3, 0xD1FFAB1E
-            slli           a3, a3, 20
-            add            a3, a3, t6
+            auipc          a3, 0xD1FFAB1E
+            addi           a3, a3, 0xD1FFAB1E
             add            a2, a2, a3
             jr             a2
-						;; size=64 bbWeight=1 PerfScore 19.00
+						;; size=52 bbWeight=1 PerfScore 14.00
 G_M20649_IG03:        ; bbWeight=0.36, gcrefRegs=0400 {a0}, byrefRegs=0000 {}, byref
             ld             a0, 0xD1FFAB1E(a0)
 						;; size=4 bbWeight=0.36 PerfScore 0.73
@@ -78,7 +75,7 @@ RWD00  	dd	G_M20649_IG05 - G_M20649_IG02
        	dd	G_M20649_IG06 - G_M20649_IG02
 
 
-; Total bytes of code 140, prolog size 16, PerfScore 38.45, instruction count 30, allocated bytes for code 140 (MethodHash=a2b0af56) for method Microsoft.CodeAnalysis.CSharp.Syntax.InternalSyntax.CompilationUnitSyntax:GetSlot(int):Microsoft.CodeAnalysis.GreenNode:this (Tier1)
+; Total bytes of code 128, prolog size 16, PerfScore 33.45, instruction count 30, allocated bytes for code 128 (MethodHash=a2b0af56) for method Microsoft.CodeAnalysis.CSharp.Syntax.InternalSyntax.CompilationUnitSyntax:GetSlot(int):Microsoft.CodeAnalysis.GreenNode:this (Tier1)
 ; ============================================================
 
 Unwind Info:
@@ -89,7 +86,7 @@ Unwind Info:
   E bit             : 0
   X bit             : 0
   Vers              : 0
-  Function Length   : 35 (0x00023) Actual length = 140 (0x00008c)
+  Function Length   : 32 (0x00020) Actual length = 128 (0x000080)
   ---- Epilog scopes ----
   ---- Scope 0
   Epilog Start Offset        : 3523193630 (0xd1ffab1e) Actual offset = 3523193630 (0xd1ffab1e) Offset from main function begin = 3523193630 (0xd1ffab1e)

+0 (0.00%) : 12080.dasm - IDEAEncryption:de_key_idea(char[],char[]) (Instrumented Tier0)

@@ -778,8 +778,8 @@ G_M48916_IG08:        ; bbWeight=1, extend
 						;; size=32 bbWeight=1 PerfScore 20.00
 G_M48916_IG09:        ; bbWeight=1, gcrefRegs=0000 {}, byrefRegs=0000 {}, byref
             ; byrRegs -[a0]
-            auipc          t6, 0xD1FFAB1E
-            ld             a0, 0xD1FFAB1E(t6)
+            auipc          a0, 0xD1FFAB1E
+            ld             a0, 0xD1FFAB1E(a0)
             lui            a1, 0xD1FFAB1E
             addiw          a1, a1, 0xD1FFAB1E
             slli           a1, a1, 32

+0 (0.00%) : 12048.dasm - AssignJagged:Run():double:this (Tier1)

@@ -322,8 +322,8 @@ G_M27632_IG17:        ; bbWeight=15.53, gcVars=0000200001000000 {V00 V01}, gcref
             bnez           t6, G_M27632_IG40
 						;; size=84 bbWeight=15.53 PerfScore 450.49
 G_M27632_IG18:        ; bbWeight=15.53, gcrefRegs=0000 {}, byrefRegs=0000 {}, byref
-            auipc          t6, 0xD1FFAB1E
-            ld             a0, 0xD1FFAB1E(t6)
+            auipc          a0, 0xD1FFAB1E
+            ld             a0, 0xD1FFAB1E(a0)
             mulh           a0, a0, s3
             srli           a1, a0, 63
             srai           a0, a0, 7

+0 (0.00%) : 12032.dasm - AssignJagged:second_assignments(int[][],short[][]) (Instrumented Tier0)

@@ -132,8 +132,8 @@ G_M6376_IG06:        ; bbWeight=1, gcrefRegs=0000 {}, byrefRegs=0000 {}, byref
             j              G_M6376_IG08
 						;; size=24 bbWeight=1 PerfScore 12.00
 G_M6376_IG07:        ; bbWeight=1, gcrefRegs=0000 {}, byrefRegs=0000 {}, byref
-            auipc          t6, 0xD1FFAB1E
-            ld             a0, 0xD1FFAB1E(t6)
+            auipc          a0, 0xD1FFAB1E
+            ld             a0, 0xD1FFAB1E(a0)
             lui            a1, 0xD1FFAB1E
             addiw          a1, a1, 0xD1FFAB1E
             slli           a1, a1, 32
@@ -230,8 +230,8 @@ G_M6376_IG12:        ; bbWeight=1, gcrefRegs=0000 {}, byrefRegs=0000 {}, byref
             j              G_M6376_IG17
 						;; size=124 bbWeight=1 PerfScore 49.00
 G_M6376_IG13:        ; bbWeight=1, gcrefRegs=0000 {}, byrefRegs=0000 {}, byref
-            auipc          t6, 0xD1FFAB1E
-            ld             a0, 0xD1FFAB1E(t6)
+            auipc          a0, 0xD1FFAB1E
+            ld             a0, 0xD1FFAB1E(a0)
             lui            a1, 0xD1FFAB1E
             addiw          a1, a1, 0xD1FFAB1E
             slli           a1, a1, 32
@@ -296,8 +296,8 @@ G_M6376_IG17:        ; bbWeight=1, gcrefRegs=0000 {}, byrefRegs=0000 {}, byref
 						;; size=84 bbWeight=1 PerfScore 33.00
 G_M6376_IG18:        ; bbWeight=1, gcrefRegs=0000 {}, byrefRegs=0000 {}, byref
             ; byrRegs -[a0]
-            auipc          t6, 0xD1FFAB1E
-            ld             a0, 0xD1FFAB1E(t6)
+            auipc          a0, 0xD1FFAB1E
+            ld             a0, 0xD1FFAB1E(a0)
             lui            a1, 0xD1FFAB1E
             addiw          a1, a1, 0xD1FFAB1E
             slli           a1, a1, 32
@@ -424,8 +424,8 @@ G_M6376_IG26:        ; bbWeight=1, gcrefRegs=0000 {}, byrefRegs=0000 {}, byref
 						;; size=132 bbWeight=1 PerfScore 54.00
 G_M6376_IG27:        ; bbWeight=1, gcrefRegs=0000 {}, byrefRegs=0000 {}, byref
             ; byrRegs -[a0]
-            auipc          t6, 0xD1FFAB1E
-            ld             a0, 0xD1FFAB1E(t6)
+            auipc          a0, 0xD1FFAB1E
+            ld             a0, 0xD1FFAB1E(a0)
             lui            a1, 0xD1FFAB1E
             addiw          a1, a1, 0xD1FFAB1E
             slli           a1, a1, 32
@@ -475,8 +475,8 @@ G_M6376_IG31:        ; bbWeight=0.50, gcrefRegs=0000 {}, byrefRegs=0000 {}, byre
             ; gcr arg pop 0
 						;; size=40 bbWeight=0.50 PerfScore 6.00
 G_M6376_IG32:        ; bbWeight=1, gcrefRegs=0000 {}, byrefRegs=0000 {}, byref
-            auipc          t6, 0xD1FFAB1E
-            ld             a0, 0xD1FFAB1E(t6)
+            auipc          a0, 0xD1FFAB1E
+            ld             a0, 0xD1FFAB1E(a0)
             lui            a1, 0xD1FFAB1E
             addiw          a1, a1, 0xD1FFAB1E
             slli           a1, a1, 32
@@ -600,8 +600,8 @@ G_M6376_IG37:        ; bbWeight=1, gcrefRegs=0000 {}, byrefRegs=0000 {}, byref
             sw             a0, -52(fp)
 						;; size=192 bbWeight=1 PerfScore 80.50
 G_M6376_IG38:        ; bbWeight=1, gcrefRegs=0000 {}, byrefRegs=0000 {}, byref
-            auipc          t6, 0xD1FFAB1E
-            ld             a0, 0xD1FFAB1E(t6)
+            auipc          a0, 0xD1FFAB1E
+            ld             a0, 0xD1FFAB1E(a0)
             lui            a1, 0xD1FFAB1E
             addiw          a1, a1, 0xD1FFAB1E
             slli           a1, a1, 32
@@ -651,8 +651,8 @@ G_M6376_IG42:        ; bbWeight=0.50, gcrefRegs=0000 {}, byrefRegs=0000 {}, byre
             ; gcr arg pop 0
 						;; size=40 bbWeight=0.50 PerfScore 6.00
 G_M6376_IG43:        ; bbWeight=1, gcrefRegs=0000 {}, byrefRegs=0000 {}, byref
-            auipc          t6, 0xD1FFAB1E
-            ld             a0, 0xD1FFAB1E(t6)
+            auipc          a0, 0xD1FFAB1E
+            ld             a0, 0xD1FFAB1E(a0)
             lui            a1, 0xD1FFAB1E
             addiw          a1, a1, 0xD1FFAB1E
             slli           a1, a1, 32
@@ -711,8 +711,8 @@ G_M6376_IG47:        ; bbWeight=0.50, gcrefRegs=0000 {}, byrefRegs=0000 {}, byre
             j              G_M6376_IG22
 						;; size=44 bbWeight=0.50 PerfScore 6.75
 G_M6376_IG48:        ; bbWeight=0.50, gcrefRegs=0000 {}, byrefRegs=0000 {}, byref
-            auipc          t6, 0xD1FFAB1E
-            ld             a0, 0xD1FFAB1E(t6)
+            auipc          a0, 0xD1FFAB1E
+            ld             a0, 0xD1FFAB1E(a0)
             lui            a1, 0xD1FFAB1E
             addiw          a1, a1, 0xD1FFAB1E
             slli           a1, a1, 32
@@ -813,8 +813,8 @@ G_M6376_IG50:        ; bbWeight=1, gcrefRegs=0000 {}, byrefRegs=0000 {}, byref
             sw             a0, -44(fp)
 						;; size=204 bbWeight=1 PerfScore 86.50
 G_M6376_IG51:        ; bbWeight=1, gcrefRegs=0000 {}, byrefRegs=0000 {}, byref
-            auipc          t6, 0xD1FFAB1E
-            ld             a0, 0xD1FFAB1E(t6)
+            auipc          a0, 0xD1FFAB1E
+            ld             a0, 0xD1FFAB1E(a0)
             lui            a1, 0xD1FFAB1E
             addiw          a1, a1, 0xD1FFAB1E
             slli           a1, a1, 32
@@ -864,8 +864,8 @@ G_M6376_IG55:        ; bbWeight=0.50, gcrefRegs=0000 {}, byrefRegs=0000 {}, byre
             ; gcr arg pop 0
 						;; size=40 bbWeight=0.50 PerfScore 6.00
 G_M6376_IG56:        ; bbWeight=1, gcrefRegs=0000 {}, byrefRegs=0000 {}, byref
-            auipc          t6, 0xD1FFAB1E
-            ld             a0, 0xD1FFAB1E(t6)
+            auipc          a0, 0xD1FFAB1E
+            ld             a0, 0xD1FFAB1E(a0)
             lui            a1, 0xD1FFAB1E
             addiw          a1, a1, 0xD1FFAB1E
             slli           a1, a1, 32
@@ -949,8 +949,8 @@ G_M6376_IG62:        ; bbWeight=1, gcrefRegs=0000 {}, byrefRegs=0000 {}, byref
             sext.w         t6, a0
             addi           ra, zero, 0xD1FFAB1E
             beq            t6, ra, G_M6376_IG63
-            auipc          t6, 0xD1FFAB1E
-            ld             a0, 0xD1FFAB1E(t6)
+            auipc          a0, 0xD1FFAB1E
+            ld             a0, 0xD1FFAB1E(a0)
             lui            a1, 0xD1FFAB1E
             addiw          a1, a1, 0xD1FFAB1E
             slli           a1, a1, 32
@@ -1029,8 +1029,8 @@ G_M6376_IG66:        ; bbWeight=1, gcrefRegs=0000 {}, byrefRegs=0000 {}, byref
             blt            t6, ra, G_M6376_IG62
 						;; size=16 bbWeight=1 PerfScore 6.50
 G_M6376_IG67:        ; bbWeight=0.50, gcrefRegs=0000 {}, byrefRegs=0000 {}, byref
-            auipc          t6, 0xD1FFAB1E
-            ld             a0, 0xD1FFAB1E(t6)
+            auipc          a0, 0xD1FFAB1E
+            ld             a0, 0xD1FFAB1E(a0)
             lui            a1, 0xD1FFAB1E
             addiw          a1, a1, 0xD1FFAB1E
             slli           a1, a1, 32
@@ -1113,8 +1113,8 @@ G_M6376_IG73:        ; bbWeight=1, gcrefRegs=0000 {}, byrefRegs=0000 {}, byref
             sext.w         t6, a0
             addi           ra, zero, 0xD1FFAB1E
             bne            t6, ra, G_M6376_IG74
-            auipc          t6, 0xD1FFAB1E
-            ld             a0, 0xD1FFAB1E(t6)
+            auipc          a0, 0xD1FFAB1E
+            ld             a0, 0xD1FFAB1E(a0)
             lui            a1, 0xD1FFAB1E
             addiw          a1, a1, 0xD1FFAB1E
             slli           a1, a1, 32
@@ -1193,8 +1193,8 @@ G_M6376_IG77:        ; bbWeight=1, gcrefRegs=0000 {}, byrefRegs=0000 {}, byref
             blt            t6, ra, G_M6376_IG73
 						;; size=16 bbWeight=1 PerfScore 6.50
 G_M6376_IG78:        ; bbWeight=0.50, gcrefRegs=0000 {}, byrefRegs=0000 {}, byref
-            auipc          t6, 0xD1FFAB1E
-            ld             a0, 0xD1FFAB1E(t6)
+            auipc          a0, 0xD1FFAB1E
+            ld             a0, 0xD1FFAB1E(a0)
             lui            a1, 0xD1FFAB1E
             addiw          a1, a1, 0xD1FFAB1E
             slli           a1, a1, 32
@@ -1242,8 +1242,8 @@ G_M6376_IG82:        ; bbWeight=1, gcrefRegs=0000 {}, byrefRegs=0000 {}, byref
             sext.w         t6, a0
             addi           ra, zero, 0xD1FFAB1E
             blt            t6, ra, G_M6376_IG72
-            auipc          t6, 0xD1FFAB1E
-            ld             a0, 0xD1FFAB1E(t6)
+            auipc          a0, 0xD1FFAB1E
+            ld             a0, 0xD1FFAB1E(a0)
             lui            a1, 0xD1FFAB1E
             addiw          a1, a1, 0xD1FFAB1E
             slli           a1, a1, 32

Details

Size improvements/regressions per collection

Collection	Contexts with diffs	Improvements	Regressions	Same size	Improvements (bytes)	Regressions (bytes)
test.mch	1,873	626	0	1,247	-9,576	+0

PerfScore improvements/regressions per collection

Collection	Contexts with diffs	Improvements	Regressions	Same PerfScore	Improvements (PerfScore)	Regressions (PerfScore)	PerfScore Overall in FullOpts
test.mch	1,873	582	0	1,291	-1.58%	0.00%	-0.1680%

Context information

Collection	Diffed contexts	MinOpts	FullOpts	Missed, base	Missed, diff
test.mch	12,289	10,113	2,176	0 (0.00%)	0 (0.00%)

jit-analyze output

am11 · 2025-06-18T12:13:16Z

Either way, code sizes >2 Gb aren't likely, assuming them as default complicates the output asm.

What would it take to synthetically reproduce a scenario like that?

tomeksowi · 2025-06-18T12:28:03Z

What would it take to synthetically reproduce a scenario like that?

Just an artificially large test, I guess. The more interesting question is whether supporting >2Gb code has any added value to the end user (if such test wasn't developed yet, I would guess not).

jkotas · 2025-06-18T12:40:36Z

Sizes throughout the code manager and the JIT are limited to 32-bit. For example:

runtime/src/coreclr/inc/corjit.h

Lines 82 to 86 in f1a4b89

    
           // Input arguments 
        
           uint32_t hotCodeSize; 
        
           uint32_t coldCodeSize; 
        
           uint32_t roDataSize; 
        
           uint32_t xcptnsCount;

. We are not interested in fixing this limitation. We just want to make sure that there are no silent integer overflows.

jkotas · 2025-06-18T13:07:00Z

For example,

runtime/src/coreclr/jit/emit.cpp

Lines 4474 to 4479 in 5951ad2

    
           for (ig = emitIGlist, offs = 0; ig; ig = ig->igNext) 
        
           { 
        
               ig->igOffs = offs; 
        
               assert(IsCodeAligned(ig->igOffs)); 
        
               offs += ig->igSize; 
        
           }

looks suspect. It is not clear what prevents silent integer oveflows in this method.

tomeksowi added 6 commits June 18, 2025 09:04

Emit auipc+addi for non-reloc label addresses

5003398

Emit auipc+jalr for INS_OPT_JALR

58ea0cc

Fix jal target register

a4878f4

Fold branches for forward and backward jumps

33f52a6

Emit auipc+load/addi for cold sections INS_OPTS_RC

5aa7a52

cleanup

fc376f2

github-actions bot added the area-CodeGen-coreclr CLR JIT compiler in src/coreclr/src/jit and related components such as SuperPMI label Jun 18, 2025

dotnet-policy-service bot added the community-contribution Indicates that the PR has been added by a community member label Jun 18, 2025

am11 added arch-riscv Related to the RISC-V architecture labels Jun 18, 2025

This was referenced Jun 18, 2025

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[RISC-V] Use auipc for all code addresses #116780

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