diff options
| -rw-r--r-- | llvm/lib/Transforms/InstCombine/InstructionCombining.cpp | 12 | ||||
| -rw-r--r-- | llvm/test/Transforms/InstCombine/zext-phi.ll | 9 |
2 files changed, 14 insertions, 7 deletions
diff --git a/llvm/lib/Transforms/InstCombine/InstructionCombining.cpp b/llvm/lib/Transforms/InstCombine/InstructionCombining.cpp index 851569c4a3d..b74b3273acd 100644 --- a/llvm/lib/Transforms/InstCombine/InstructionCombining.cpp +++ b/llvm/lib/Transforms/InstCombine/InstructionCombining.cpp @@ -89,11 +89,13 @@ Value *InstCombiner::EmitGEPOffset(User *GEP) { /// Return true if it is desirable to convert an integer computation from a /// given bit width to a new bit width. /// We don't want to convert from a legal to an illegal type or from a smaller -/// to a larger illegal type. +/// to a larger illegal type. A width of '1' is always treated as a legal type +/// because i1 is a fundamental type in IR, and there are many specialized +/// optimizations for i1 types. bool InstCombiner::shouldChangeType(unsigned FromWidth, unsigned ToWidth) const { - bool FromLegal = DL.isLegalInteger(FromWidth); - bool ToLegal = DL.isLegalInteger(ToWidth); + bool FromLegal = FromWidth == 1 || DL.isLegalInteger(FromWidth); + bool ToLegal = ToWidth == 1 || DL.isLegalInteger(ToWidth); // If this is a legal integer from type, and the result would be an illegal // type, don't do the transformation. @@ -110,7 +112,9 @@ bool InstCombiner::shouldChangeType(unsigned FromWidth, /// Return true if it is desirable to convert a computation from 'From' to 'To'. /// We don't want to convert from a legal to an illegal type or from a smaller -/// to a larger illegal type. +/// to a larger illegal type. i1 is always treated as a legal type because it is +/// a fundamental type in IR, and there are many specialized optimizations for +/// i1 types. bool InstCombiner::shouldChangeType(Type *From, Type *To) const { assert(From->isIntegerTy() && To->isIntegerTy()); diff --git a/llvm/test/Transforms/InstCombine/zext-phi.ll b/llvm/test/Transforms/InstCombine/zext-phi.ll index 5d64b0582f0..5e352415c74 100644 --- a/llvm/test/Transforms/InstCombine/zext-phi.ll +++ b/llvm/test/Transforms/InstCombine/zext-phi.ll @@ -2,16 +2,19 @@ target datalayout = "e-m:e-i64:64-n8:16:32:64" +; Although i1 is not in the datalayout, we should treat it +; as a legal type because it is a fundamental type in IR. +; This means we should shrink the phi (sink the zexts). + define i64 @sink_i1_casts(i1 %cond1, i1 %cond2) { ; CHECK-LABEL: @sink_i1_casts( ; CHECK-NEXT: entry: -; CHECK-NEXT: [[Z1:%.*]] = zext i1 %cond1 to i64 ; CHECK-NEXT: br i1 %cond1, label %if, label %end ; CHECK: if: -; CHECK-NEXT: [[Z2:%.*]] = zext i1 %cond2 to i64 ; CHECK-NEXT: br label %end ; CHECK: end: -; CHECK-NEXT: [[PHI:%.*]] = phi i64 [ [[Z1]], %entry ], [ [[Z2]], %if ] +; CHECK-NEXT: [[PHI_IN:%.*]] = phi i1 [ %cond1, %entry ], [ %cond2, %if ] +; CHECK-NEXT: [[PHI:%.*]] = zext i1 [[PHI_IN]] to i64 ; CHECK-NEXT: ret i64 [[PHI]] ; entry: |
