[llvm] 5450963 - [InstCombine] Check source element type in phi of gep fold

[Nikita Popov via llvm-commits]

Author: Nikita Popov
Date: 2022-02-11T14:26:18+01:00
New Revision: 545096308586feae7dfdaea62e0145dc9ffe3728

URL: https://github.com/llvm/llvm-project/commit/545096308586feae7dfdaea62e0145dc9ffe3728
DIFF: https://github.com/llvm/llvm-project/commit/545096308586feae7dfdaea62e0145dc9ffe3728.diff

LOG: [InstCombine] Check source element type in phi of gep fold

Rather than checking that the type is the same (which is always
the case, given how these are part of the same phi) check that the
source element type is the same. With opaque pointers, this is no
longer implied.

Added: 
    

Modified: 
    llvm/lib/Transforms/InstCombine/InstCombinePHI.cpp
    llvm/test/Transforms/InstCombine/opaque-ptr.ll

Removed: 
    


################################################################################
diff  --git a/llvm/lib/Transforms/InstCombine/InstCombinePHI.cpp b/llvm/lib/Transforms/InstCombine/InstCombinePHI.cpp
index 09694d50468f0..13277e8727597 100644
--- a/llvm/lib/Transforms/InstCombine/InstCombinePHI.cpp
+++ b/llvm/lib/Transforms/InstCombine/InstCombinePHI.cpp
@@ -511,7 +511,8 @@ Instruction *InstCombinerImpl::foldPHIArgGEPIntoPHI(PHINode &PN) {
   // Scan to see if all operands are the same opcode, and all have one user.
   for (Value *V : drop_begin(PN.incoming_values())) {
     GetElementPtrInst *GEP = dyn_cast<GetElementPtrInst>(V);
-    if (!GEP || !GEP->hasOneUser() || GEP->getType() != FirstInst->getType() ||
+    if (!GEP || !GEP->hasOneUser() ||
+        GEP->getSourceElementType() != FirstInst->getSourceElementType() ||
         GEP->getNumOperands() != FirstInst->getNumOperands())
       return nullptr;
 

diff  --git a/llvm/test/Transforms/InstCombine/opaque-ptr.ll b/llvm/test/Transforms/InstCombine/opaque-ptr.ll
index f054df6244e13..9da3618913db6 100644
--- a/llvm/test/Transforms/InstCombine/opaque-ptr.ll
+++ b/llvm/test/Transforms/InstCombine/opaque-ptr.ll
@@ -344,3 +344,57 @@ define i1 @cmp_load_gep_global_
diff erent_gep_type(i64 %idx) {
   %cmp = icmp eq i16 %load, 3
   ret i1 %cmp
 }
+
+define ptr @phi_of_gep(i1 %c, ptr %p) {
+; CHECK-LABEL: @phi_of_gep(
+; CHECK-NEXT:    br i1 [[C:%.*]], label [[IF:%.*]], label [[ELSE:%.*]]
+; CHECK:       if:
+; CHECK-NEXT:    br label [[JOIN:%.*]]
+; CHECK:       else:
+; CHECK-NEXT:    br label [[JOIN]]
+; CHECK:       join:
+; CHECK-NEXT:    [[PHI:%.*]] = getelementptr i32, ptr [[P:%.*]], i64 1
+; CHECK-NEXT:    ret ptr [[PHI]]
+;
+  br i1 %c, label %if, label %else
+
+if:
+  %gep1 = getelementptr i32, ptr %p, i64 1
+  br label %join
+
+else:
+  %gep2 = getelementptr i32, ptr %p, i64 1
+  br label %join
+
+join:
+  %phi = phi ptr [ %gep1, %if ], [ %gep2, %else ]
+  ret ptr %phi
+}
+
+define ptr @phi_of_gep_
diff erent_type(i1 %c, ptr %p) {
+; CHECK-LABEL: @phi_of_gep_
diff erent_type(
+; CHECK-NEXT:    br i1 [[C:%.*]], label [[IF:%.*]], label [[ELSE:%.*]]
+; CHECK:       if:
+; CHECK-NEXT:    [[GEP1:%.*]] = getelementptr i32, ptr [[P:%.*]], i64 1
+; CHECK-NEXT:    br label [[JOIN:%.*]]
+; CHECK:       else:
+; CHECK-NEXT:    [[GEP2:%.*]] = getelementptr i64, ptr [[P]], i64 1
+; CHECK-NEXT:    br label [[JOIN]]
+; CHECK:       join:
+; CHECK-NEXT:    [[PHI:%.*]] = phi ptr [ [[GEP1]], [[IF]] ], [ [[GEP2]], [[ELSE]] ]
+; CHECK-NEXT:    ret ptr [[PHI]]
+;
+  br i1 %c, label %if, label %else
+
+if:
+  %gep1 = getelementptr i32, ptr %p, i64 1
+  br label %join
+
+else:
+  %gep2 = getelementptr i64, ptr %p, i64 1
+  br label %join
+
+join:
+  %phi = phi ptr [ %gep1, %if ], [ %gep2, %else ]
+  ret ptr %phi
+}