Fix handling of dontcall attributes for arches that lower calls via fastSelectInstruction

[dpaoliello]

Recently my change to avoid duplicate dontcall attribute errors (#152810) caused the Clang Frontend/backend-attribute-error-warning.c test to fail on Arm32: https://lab.llvm.org/buildbot/#/builders/154/builds/20134

The root cause is that, if the default IFastSel path bails, then targets are given the opportunity to lower instructions via fastSelectInstruction. That's the path taken by Arm32 and since its implementation of selectCall didn't call diagnoseDontCall no error was emitted.

I've checked the other implementations of fastSelectInstruction and the only other one that lowers call instructions in WebAssembly, so I've fixed that too.

[llvmbot]

@llvm/pr-subscribers-backend-arm

@llvm/pr-subscribers-backend-webassembly

Author: Daniel Paoliello (dpaoliello)

Changes

Recently my change to avoid duplicate dontcall attribute errors (#152810) caused the Clang Frontend/backend-attribute-error-warning.c test to fail on Arm32: <https://lab.llvm.org/buildbot/#/builders/154/builds/20134>

The root cause is that, if the default IFastSel path bails, then targets are given the opportunity to lower instructions via fastSelectInstruction. That's the path taken by Arm32 and since its implementation of selectCall didn't call diagnoseDontCall no error was emitted.

I've checked the other implementations of fastSelectInstruction and the only other one that lowers call instructions in WebAssembly, so I've fixed that too.

---

Full diff: https://github.com/llvm/llvm-project/pull/153302.diff

2 Files Affected:

• (modified) llvm/lib/Target/ARM/ARMFastISel.cpp (+1)
• (modified) llvm/lib/Target/WebAssembly/WebAssemblyFastISel.cpp (+2)

diff --git a/llvm/lib/Target/ARM/ARMFastISel.cpp b/llvm/lib/Target/ARM/ARMFastISel.cpp
index 54aa355d4db0a..14e1160e70dae 100644
--- a/llvm/lib/Target/ARM/ARMFastISel.cpp
+++ b/llvm/lib/Target/ARM/ARMFastISel.cpp
@@ -2504,6 +2504,7 @@ bool ARMFastISel::SelectCall(const Instruction *I,
   // Set all unused physreg defs as dead.
   static_cast<MachineInstr *>(MIB)->setPhysRegsDeadExcept(UsedRegs, TRI);
 
+  diagnoseDontCall(*CI);
   return true;
 }
 
diff --git a/llvm/lib/Target/WebAssembly/WebAssemblyFastISel.cpp b/llvm/lib/Target/WebAssembly/WebAssemblyFastISel.cpp
index ec95e86e4fe3d..2666342d0c7b9 100644
--- a/llvm/lib/Target/WebAssembly/WebAssemblyFastISel.cpp
+++ b/llvm/lib/Target/WebAssembly/WebAssemblyFastISel.cpp
@@ -912,6 +912,8 @@ bool WebAssemblyFastISel::selectCall(const Instruction *I) {
 
   if (!IsVoid)
     updateValueMap(Call, ResultReg);
+
+  diagnoseDontCall(*Call);
   return true;
 }