[llvm] r277767 - GVNHoist: Don't hoist convergent calls

[Matt Arsenault via llvm-commits]

Author: arsenm
Date: Thu Aug  4 15:52:57 2016
New Revision: 277767

URL: http://llvm.org/viewvc/llvm-project?rev=277767&view=rev
Log:
GVNHoist: Don't hoist convergent calls

Added:
    llvm/trunk/test/Transforms/GVN/hoist-convergent.ll
Modified:
    llvm/trunk/lib/Transforms/Scalar/GVNHoist.cpp

Modified: llvm/trunk/lib/Transforms/Scalar/GVNHoist.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Transforms/Scalar/GVNHoist.cpp?rev=277767&r1=277766&r2=277767&view=diff
==============================================================================
--- llvm/trunk/lib/Transforms/Scalar/GVNHoist.cpp (original)
+++ llvm/trunk/lib/Transforms/Scalar/GVNHoist.cpp Thu Aug  4 15:52:57 2016
@@ -879,6 +879,10 @@ private:
             if (Call->mayThrow())
               break;
           }
+
+          if (Call->isConvergent())
+            break;
+
           CI.insert(Call, VN);
         } else if (HoistingGeps || !isa<GetElementPtrInst>(&I1))
           // Do not hoist scalars past calls that may write to memory because

Added: llvm/trunk/test/Transforms/GVN/hoist-convergent.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/Transforms/GVN/hoist-convergent.ll?rev=277767&view=auto
==============================================================================
--- llvm/trunk/test/Transforms/GVN/hoist-convergent.ll (added)
+++ llvm/trunk/test/Transforms/GVN/hoist-convergent.ll Thu Aug  4 15:52:57 2016
@@ -0,0 +1,93 @@
+; RUN: opt -gvn-hoist -S < %s | FileCheck %s
+
+; Check that convergent calls are not hoisted.
+;
+; CHECK-LABEL: @no_convergent_func_hoisting(
+; CHECK: if.then:
+; CHECK: call float @convergent_func(
+
+; CHECK: if.else:
+; CHECK: call float @convergent_func(
+define float @no_convergent_func_hoisting(float %d, float %min, float %max, float %a) {
+entry:
+  %div = fdiv float 1.000000e+00, %d
+  %cmp = fcmp oge float %div, 0.000000e+00
+  br i1 %cmp, label %if.then, label %if.else
+
+if.then:
+  %sub1 = fsub float %max, %a
+  %mul2 = call float @convergent_func(float %sub1, float %div)
+  br label %if.end
+
+if.else:
+  %sub5 = fsub float %max, %a
+  %mul6 = call float @convergent_func(float %sub5, float %div)
+  br label %if.end
+
+if.end:
+  %tmax.0 = phi float [ %mul2, %if.then ], [ %mul6, %if.else ]
+  %add = fadd float %tmax.0, 10.0
+  ret float %add
+}
+
+; The call site is convergent but the declaration is not.
+; CHECK-LABEL: @no_convergent_call_hoisting(
+
+; CHECK: if.then:
+; CHECK: call float @func(
+
+; CHECK: if.else:
+; CHECK: call float @func(
+define float @no_convergent_call_hoisting(float %d, float %min, float %max, float %a) {
+entry:
+  %div = fdiv float 1.000000e+00, %d
+  %cmp = fcmp oge float %div, 0.000000e+00
+  br i1 %cmp, label %if.then, label %if.else
+
+if.then:
+  %sub1 = fsub float %max, %a
+  %mul2 = call float @func(float %sub1, float %div) #0
+  br label %if.end
+
+if.else:
+  %sub5 = fsub float %max, %a
+  %mul6 = call float @func(float %sub5, float %div) #0
+  br label %if.end
+
+if.end:
+  %tmax.0 = phi float [ %mul2, %if.then ], [ %mul6, %if.else ]
+  %add = fadd float %tmax.0, 10.0
+  ret float %add
+}
+
+; The call site is convergent but the declaration is not.
+; CHECK-LABEL: @call_hoisting(
+; CHECK: call float @func(
+; CHECK-NOT: call float @func(
+define float @call_hoisting(float %d, float %min, float %max, float %a) {
+entry:
+  %div = fdiv float 1.000000e+00, %d
+  %cmp = fcmp oge float %div, 0.000000e+00
+  br i1 %cmp, label %if.then, label %if.else
+
+if.then:
+  %sub1 = fsub float %max, %a
+  %mul2 = call float @func(float %sub1, float %div)
+  br label %if.end
+
+if.else:
+  %sub5 = fsub float %max, %a
+  %mul6 = call float @func(float %sub5, float %div)
+  br label %if.end
+
+if.end:
+  %tmax.0 = phi float [ %mul2, %if.then ], [ %mul6, %if.else ]
+  %add = fadd float %tmax.0, 10.0
+  ret float %add
+}
+
+declare float @convergent_func(float, float) #0
+declare float @func(float, float) #1
+
+attributes #0 = { nounwind readnone convergent }
+attributes #1 = { nounwind readnone }