[llvm] 0489b48 - Mips/GlobalISel: Fix adding $gp to calls as a def instead of a use (#227679)

[via llvm-commits]

Author: Matt Arsenault
Date: 2026-10-01T14:02:59+02:00
New Revision: 0489b48e2f2e2374bee7db19483322307d19b8bf

URL: https://github.com/llvm/llvm-project/commit/0489b48e2f2e2374bee7db19483322307d19b8bf
DIFF: https://github.com/llvm/llvm-project/commit/0489b48e2f2e2374bee7db19483322307d19b8bf.diff

LOG: Mips/GlobalISel: Fix adding $gp to calls as a def instead of a use (#227679)

A PIC call needs $gp to point at the GOT for the lazy binding stub.
SelectionDAG adds it as an ordinary argument register. GlobalISel
instead added it as an implicit def, which killed the $gp copy set up
right before the call.

Co-authored-by: Claude Opus 5 <noreply at anthropic.com>

Added: 
    

Modified: 
    llvm/lib/Target/Mips/MipsCallLowering.cpp
    llvm/test/CodeGen/Mips/GlobalISel/irtranslator/call.ll
    llvm/test/CodeGen/Mips/GlobalISel/irtranslator/global_address_pic.ll

Removed: 
    


################################################################################
diff  --git a/llvm/lib/Target/Mips/MipsCallLowering.cpp b/llvm/lib/Target/Mips/MipsCallLowering.cpp
index c1407917fbb21..13c740ed1991d 100644
--- a/llvm/lib/Target/Mips/MipsCallLowering.cpp
+++ b/llvm/lib/Target/Mips/MipsCallLowering.cpp
@@ -477,7 +477,7 @@ bool MipsCallLowering::lowerCall(MachineIRBuilder &MIRBuilder,
     MIRBuilder.buildCopy(
       Register(Mips::GP),
       MF.getInfo<MipsFunctionInfo>()->getGlobalBaseRegForGlobalISel(MF));
-    MIB.addDef(Mips::GP, RegState::Implicit);
+    MIB.addUse(Mips::GP, RegState::Implicit);
   }
   MIRBuilder.insertInstr(MIB);
   if (MIB->getOpcode() == Mips::JALRPseudo) {

diff  --git a/llvm/test/CodeGen/Mips/GlobalISel/irtranslator/call.ll b/llvm/test/CodeGen/Mips/GlobalISel/irtranslator/call.ll
index fb8e47e10b12f..34fedf4e866a2 100644
--- a/llvm/test/CodeGen/Mips/GlobalISel/irtranslator/call.ll
+++ b/llvm/test/CodeGen/Mips/GlobalISel/irtranslator/call.ll
@@ -34,7 +34,7 @@ define i32 @call_global(i32 %a0, i32 %a1, i32 %x, i32 %y) {
   ; MIPS32_PIC:   $a0 = COPY [[COPY2]](s32)
   ; MIPS32_PIC:   $a1 = COPY [[COPY3]](s32)
   ; MIPS32_PIC:   $gp = COPY [[ADDu]]
-  ; MIPS32_PIC:   JALRPseudo [[GV]](p0), csr_o32, implicit-def dead $ra, implicit-def $sp, implicit $a0, implicit $a1, implicit-def $gp, implicit-def $v0
+  ; MIPS32_PIC:   JALRPseudo [[GV]](p0), csr_o32, implicit-def dead $ra, implicit-def $sp, implicit $a0, implicit $a1, implicit $gp, implicit-def $v0
   ; MIPS32_PIC:   [[COPY4:%[0-9]+]]:_(s32) = COPY $v0
   ; MIPS32_PIC:   ADJCALLSTACKUP 16, 0, implicit-def $sp, implicit $sp
   ; MIPS32_PIC:   [[ADD:%[0-9]+]]:_(s32) = G_ADD [[COPY4]], [[COPY4]]
@@ -98,7 +98,7 @@ define i32 @call_global_with_local_linkage(i32 %a0, i32 %a1, i32 %x, i32 %y) {
   ; MIPS32_PIC:   $a0 = COPY [[COPY2]](s32)
   ; MIPS32_PIC:   $a1 = COPY [[COPY3]](s32)
   ; MIPS32_PIC:   $gp = COPY [[ADDu]]
-  ; MIPS32_PIC:   JALRPseudo [[GV]](p0), csr_o32, implicit-def dead $ra, implicit-def $sp, implicit $a0, implicit $a1, implicit-def $gp, implicit-def $v0
+  ; MIPS32_PIC:   JALRPseudo [[GV]](p0), csr_o32, implicit-def dead $ra, implicit-def $sp, implicit $a0, implicit $a1, implicit $gp, implicit-def $v0
   ; MIPS32_PIC:   [[COPY4:%[0-9]+]]:_(s32) = COPY $v0
   ; MIPS32_PIC:   ADJCALLSTACKUP 16, 0, implicit-def $sp, implicit $sp
   ; MIPS32_PIC:   [[ADD:%[0-9]+]]:_(s32) = G_ADD [[COPY4]], [[COPY4]]
@@ -184,7 +184,7 @@ define void @call_f_with_void_ret() {
   ; MIPS32_PIC:   ADJCALLSTACKDOWN 16, 0, implicit-def $sp, implicit $sp
   ; MIPS32_PIC:   [[GV:%[0-9]+]]:gpr32(p0) = G_GLOBAL_VALUE target-flags(mips-got-call) @f_with_void_ret
   ; MIPS32_PIC:   $gp = COPY [[ADDu]]
-  ; MIPS32_PIC:   JALRPseudo [[GV]](p0), csr_o32, implicit-def dead $ra, implicit-def $sp, implicit-def $gp
+  ; MIPS32_PIC:   JALRPseudo [[GV]](p0), csr_o32, implicit-def dead $ra, implicit-def $sp, implicit $gp
   ; MIPS32_PIC:   ADJCALLSTACKUP 16, 0, implicit-def $sp, implicit $sp
   ; MIPS32_PIC:   RetRA
 entry:

diff  --git a/llvm/test/CodeGen/Mips/GlobalISel/irtranslator/global_address_pic.ll b/llvm/test/CodeGen/Mips/GlobalISel/irtranslator/global_address_pic.ll
index a61e24610292d..06af014751d14 100644
--- a/llvm/test/CodeGen/Mips/GlobalISel/irtranslator/global_address_pic.ll
+++ b/llvm/test/CodeGen/Mips/GlobalISel/irtranslator/global_address_pic.ll
@@ -29,7 +29,7 @@ define i32 @call_global(i32 %a, i32 %b) {
   ; MIPS32_PIC:   $a0 = COPY [[COPY]](s32)
   ; MIPS32_PIC:   $a1 = COPY [[COPY1]](s32)
   ; MIPS32_PIC:   $gp = COPY [[ADDu]]
-  ; MIPS32_PIC:   JALRPseudo [[GV]](p0), csr_o32, implicit-def dead $ra, implicit-def $sp, implicit $a0, implicit $a1, implicit-def $gp, implicit-def $v0
+  ; MIPS32_PIC:   JALRPseudo [[GV]](p0), csr_o32, implicit-def dead $ra, implicit-def $sp, implicit $a0, implicit $a1, implicit $gp, implicit-def $v0
   ; MIPS32_PIC:   [[COPY2:%[0-9]+]]:_(s32) = COPY $v0
   ; MIPS32_PIC:   ADJCALLSTACKUP 16, 0, implicit-def $sp, implicit $sp
   ; MIPS32_PIC:   $v0 = COPY [[COPY2]](s32)
@@ -51,7 +51,7 @@ define i32 @call_global_with_local_linkage(i32 %a, i32 %b) {
   ; MIPS32_PIC:   $a0 = COPY [[COPY]](s32)
   ; MIPS32_PIC:   $a1 = COPY [[COPY1]](s32)
   ; MIPS32_PIC:   $gp = COPY [[ADDu]]
-  ; MIPS32_PIC:   JALRPseudo [[GV]](p0), csr_o32, implicit-def dead $ra, implicit-def $sp, implicit $a0, implicit $a1, implicit-def $gp, implicit-def $v0
+  ; MIPS32_PIC:   JALRPseudo [[GV]](p0), csr_o32, implicit-def dead $ra, implicit-def $sp, implicit $a0, implicit $a1, implicit $gp, implicit-def $v0
   ; MIPS32_PIC:   [[COPY2:%[0-9]+]]:_(s32) = COPY $v0
   ; MIPS32_PIC:   ADJCALLSTACKUP 16, 0, implicit-def $sp, implicit $sp
   ; MIPS32_PIC:   $v0 = COPY [[COPY2]](s32)