[llvm] r361957 - SpeculateAroundPHIs: Respect convergent

[Matt Arsenault via llvm-commits]

Author: arsenm
Date: Wed May 29 06:14:39 2019
New Revision: 361957

URL: http://llvm.org/viewvc/llvm-project?rev=361957&view=rev
Log:
SpeculateAroundPHIs: Respect convergent

Added:
    llvm/trunk/test/Transforms/SpeculateAroundPHIs/convergent.ll
Modified:
    llvm/trunk/lib/Transforms/Scalar/SpeculateAroundPHIs.cpp

Modified: llvm/trunk/lib/Transforms/Scalar/SpeculateAroundPHIs.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Transforms/Scalar/SpeculateAroundPHIs.cpp?rev=361957&r1=361956&r2=361957&view=diff
==============================================================================
--- llvm/trunk/lib/Transforms/Scalar/SpeculateAroundPHIs.cpp (original)
+++ llvm/trunk/lib/Transforms/Scalar/SpeculateAroundPHIs.cpp Wed May 29 06:14:39 2019
@@ -67,6 +67,14 @@ isSafeToSpeculatePHIUsers(PHINode &PN, D
       return false;
     }
 
+    if (auto CS = ImmutableCallSite(UI)) {
+      if (CS.isConvergent() || CS.cannotDuplicate()) {
+        LLVM_DEBUG(dbgs() << "  Unsafe: convergent "
+                   "callsite cannot de duplicated: " << *UI << '\n');
+        return false;
+      }
+    }
+
     // FIXME: This check is much too conservative. We're not going to move these
     // instructions onto new dynamic paths through the program unless there is
     // a call instruction between the use and the PHI node. And memory isn't

Added: llvm/trunk/test/Transforms/SpeculateAroundPHIs/convergent.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/Transforms/SpeculateAroundPHIs/convergent.ll?rev=361957&view=auto
==============================================================================
--- llvm/trunk/test/Transforms/SpeculateAroundPHIs/convergent.ll (added)
+++ llvm/trunk/test/Transforms/SpeculateAroundPHIs/convergent.ll Wed May 29 06:14:39 2019
@@ -0,0 +1,98 @@
+; NOTE: Assertions have been autogenerated by utils/update_test_checks.py
+; RUN: opt -S -passes=spec-phis < %s | FileCheck %s
+; Make sure convergent and noduplicate calls aren't duplicated.
+
+declare i32 @llvm.convergent(i32) #0
+declare i32 @llvm.noduplicate(i32) #1
+declare i32 @llvm.regular(i32) #2
+
+define i32 @test_convergent(i1 %flag, i32 %arg) #0 {
+; CHECK-LABEL: @test_convergent(
+; CHECK-NEXT:  entry:
+; CHECK-NEXT:    br i1 [[FLAG:%.*]], label [[A:%.*]], label [[B:%.*]]
+; CHECK:       a:
+; CHECK-NEXT:    br label [[EXIT:%.*]]
+; CHECK:       b:
+; CHECK-NEXT:    br label [[EXIT]]
+; CHECK:       exit:
+; CHECK-NEXT:    [[P:%.*]] = phi i32 [ 7, [[A]] ], [ 11, [[B]] ]
+; CHECK-NEXT:    [[SUM:%.*]] = call i32 @llvm.convergent(i32 [[P]])
+; CHECK-NEXT:    ret i32 [[SUM]]
+;
+entry:
+  br i1 %flag, label %a, label %b
+
+a:
+  br label %exit
+
+b:
+  br label %exit
+
+exit:
+  %p = phi i32 [ 7, %a ], [ 11, %b ]
+  %sum = call i32 @llvm.convergent(i32 %p)
+  ret i32 %sum
+}
+
+define i32 @test_noduplicate(i1 %flag, i32 %arg) #1 {
+; CHECK-LABEL: @test_noduplicate(
+; CHECK-NEXT:  entry:
+; CHECK-NEXT:    br i1 [[FLAG:%.*]], label [[A:%.*]], label [[B:%.*]]
+; CHECK:       a:
+; CHECK-NEXT:    br label [[EXIT:%.*]]
+; CHECK:       b:
+; CHECK-NEXT:    br label [[EXIT]]
+; CHECK:       exit:
+; CHECK-NEXT:    [[P:%.*]] = phi i32 [ 7, [[A]] ], [ 11, [[B]] ]
+; CHECK-NEXT:    [[SUM:%.*]] = call i32 @llvm.noduplicate(i32 [[P]])
+; CHECK-NEXT:    ret i32 [[SUM]]
+;
+entry:
+  br i1 %flag, label %a, label %b
+
+a:
+  br label %exit
+
+b:
+  br label %exit
+
+exit:
+  %p = phi i32 [ 7, %a ], [ 11, %b ]
+  %sum = call i32 @llvm.noduplicate(i32 %p)
+  ret i32 %sum
+}
+
+; Otherwise identical function which should be transformed.
+define i32 @test_reference(i1 %flag, i32 %arg) #2 {
+; CHECK-LABEL: @test_reference(
+; CHECK-NEXT:  entry:
+; CHECK-NEXT:    br i1 [[FLAG:%.*]], label [[A:%.*]], label [[B:%.*]]
+; CHECK:       a:
+; CHECK-NEXT:    [[SUM_0:%.*]] = call i32 @llvm.regular(i32 7)
+; CHECK-NEXT:    br label [[EXIT:%.*]]
+; CHECK:       b:
+; CHECK-NEXT:    [[SUM_1:%.*]] = call i32 @llvm.regular(i32 11)
+; CHECK-NEXT:    br label [[EXIT]]
+; CHECK:       exit:
+; CHECK-NEXT:    [[SUM_PHI:%.*]] = phi i32 [ [[SUM_0]], [[A]] ], [ [[SUM_1]], [[B]] ]
+; CHECK-NEXT:    ret i32 [[SUM_PHI]]
+;
+entry:
+  br i1 %flag, label %a, label %b
+
+a:
+  br label %exit
+
+b:
+  br label %exit
+
+exit:
+  %p = phi i32 [ 7, %a ], [ 11, %b ]
+  %sum = call i32 @llvm.regular(i32 %p)
+  ret i32 %sum
+}
+
+
+attributes #0 = { nounwind readnone convergent speculatable }
+attributes #1 = { nounwind readnone noduplicate speculatable }
+attributes #2 = { nounwind readnone speculatable }