[PATCH] D24844: GVN-hoist: disable hoisting stores past calls (PR30499)

[Sebastian Pop via llvm-commits]

sebpop created this revision.
sebpop added a reviewer: dberlin.
sebpop added a subscriber: llvm-commits.

MemoryLocation::get() does not support CallInst and it errors with llvm_unreachable("unsupported memory instruction");
The current patch avoids calling get() with CallInst.

https://reviews.llvm.org/D24844

Files:
  llvm/lib/Transforms/Scalar/GVNHoist.cpp
  llvm/test/Transforms/GVNHoist/pr30499.ll

Index: llvm/test/Transforms/GVNHoist/pr30499.ll
===================================================================
--- /dev/null
+++ llvm/test/Transforms/GVNHoist/pr30499.ll
@@ -0,0 +1,31 @@
+; RUN: opt -S -gvn-hoist < %s
+
+define void @_Z3fn2v() #0 {
+entry:
+  %a = alloca i8*, align 8
+  %b = alloca i32, align 4
+  %0 = load i8*, i8** %a, align 8
+  store i8 0, i8* %0, align 1
+  %1 = load i32, i32* %b, align 4
+  %tobool = icmp ne i32 %1, 0
+  br i1 %tobool, label %if.then, label %if.end
+
+if.then:                                          ; preds = %entry
+  %call = call i64 @_Z3fn1v() #2
+  %conv = trunc i64 %call to i32
+  store i32 %conv, i32* %b, align 4
+  br label %if.end
+
+if.end:                                           ; preds = %if.then, %entry
+  %2 = load i8*, i8** %a, align 8
+  store i8 0, i8* %2, align 1
+  ret void
+}
+
+; Function Attrs: nounwind readonly
+declare i64 @_Z3fn1v() #1
+
+attributes #0 = { nounwind "correctly-rounded-divide-sqrt-fp-math"="false" "disable-tail-calls"="false" "less-precise-fpmad"="false" "no-frame-pointer-elim"="false" "no-infs-fp-math"="false" "no-jump-tables"="false" "no-nans-fp-math"="false" "no-signed-zeros-fp-math"="false" "no-trapping-math"="false" "stack-protector-buffer-size"="8" "target-cpu"="x86-64" "target-features"="+fxsr,+mmx,+sse,+sse2,+x87" "unsafe-fp-math"="false" "use-soft-float"="false" }
+attributes #1 = { nounwind readonly "correctly-rounded-divide-sqrt-fp-math"="false" "disable-tail-calls"="false" "less-precise-fpmad"="false" "no-frame-pointer-elim"="false" "no-infs-fp-math"="false" "no-nans-fp-math"="false" "no-signed-zeros-fp-math"="false" "no-trapping-math"="false" "stack-protector-buffer-size"="8" "target-cpu"="x86-64" "target-features"="+fxsr,+mmx,+sse,+sse2,+x87" "unsafe-fp-math"="false" "use-soft-float"="false" }
+attributes #2 = { nounwind readonly }
+
Index: llvm/lib/Transforms/Scalar/GVNHoist.cpp
===================================================================
--- llvm/lib/Transforms/Scalar/GVNHoist.cpp
+++ llvm/lib/Transforms/Scalar/GVNHoist.cpp
@@ -345,21 +345,27 @@
       auto *MU = dyn_cast<MemoryUse>(&MA);
       if (!MU)
         continue;
+      Instruction *Insn = MU->getMemoryInst();
 
       // Do not check whether MU aliases Def when MU occurs after OldPt.
-      if (BB == OldBB && firstInBB(OldPt, MU->getMemoryInst()))
+      if (BB == OldBB && firstInBB(OldPt, Insn))
         break;
 
       // Do not check whether MU aliases Def when MU occurs before NewPt.
       if (BB == NewBB) {
         if (!ReachedNewPt) {
-          if (firstInBB(MU->getMemoryInst(), NewPt))
+          if (firstInBB(Insn, NewPt))
             continue;
           ReachedNewPt = true;
         }
       }
 
-      if (!AA->isNoAlias(DefLoc, MemoryLocation::get(MU->getMemoryInst())))
+      // Do not hoist stores past calls because MemoryLocation::get() does not
+      // work for CallInst.
+      if (isa<CallInst>(Insn))
+        return true;
+
+      if (!AA->isNoAlias(DefLoc, MemoryLocation::get(Insn)))
         return true;
     }
 


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