[PATCH] D125654: [TypePromotion] Refine fix sext/zext for promoted constant from D125294.

[Craig Topper via Phabricator via llvm-commits]

This revision was not accepted when it landed; it landed in state "Needs Review".
This revision was landed with ongoing or failed builds.
This revision was automatically updated to reflect the committed changes.
Closed by commit rG4638766794b0: [TypePromotion] Refine fix sext/zext for promoted constant from D125294. (authored by craig.topper).

Changed prior to commit:
  https://reviews.llvm.org/D125654?vs=429588&id=431177#toc

Repository:
  rG LLVM Github Monorepo

CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D125654/new/

https://reviews.llvm.org/D125654

Files:
  llvm/lib/CodeGen/TypePromotion.cpp
  llvm/test/Transforms/TypePromotion/ARM/icmps.ll


Index: llvm/test/Transforms/TypePromotion/ARM/icmps.ll
===================================================================
--- llvm/test/Transforms/TypePromotion/ARM/icmps.ll
+++ llvm/test/Transforms/TypePromotion/ARM/icmps.ll
@@ -319,6 +319,24 @@
   ret i32 %conv1
 }
 
+define i32 @icmp_minus_imm_noncanonicalcmp(i8* %a) {
+; CHECK-LABEL: @icmp_minus_imm_noncanonicalcmp(
+; CHECK-NEXT:  entry:
+; CHECK-NEXT:    [[TMP0:%.*]] = load i8, i8* [[A:%.*]], align 1
+; CHECK-NEXT:    [[TMP1:%.*]] = zext i8 [[TMP0]] to i32
+; CHECK-NEXT:    [[ADD_I:%.*]] = add i32 [[TMP1]], -7
+; CHECK-NEXT:    [[CMP:%.*]] = icmp ult i32 -5, [[ADD_I]]
+; CHECK-NEXT:    [[CONV1:%.*]] = zext i1 [[CMP]] to i32
+; CHECK-NEXT:    ret i32 [[CONV1]]
+;
+entry:
+  %0 = load i8, i8* %a, align 1
+  %add.i = add i8 %0, -7
+  %cmp = icmp ult i8 -5, %add.i
+  %conv1 = zext i1 %cmp to i32
+  ret i32 %conv1
+}
+
 define void @mul_with_neg_imm(i32, i32* %b) {
 ; CHECK-LABEL: @mul_with_neg_imm(
 ; CHECK-NEXT:  entry:
Index: llvm/lib/CodeGen/TypePromotion.cpp
===================================================================
--- llvm/lib/CodeGen/TypePromotion.cpp
+++ llvm/lib/CodeGen/TypePromotion.cpp
@@ -486,7 +486,10 @@
       if (auto *Const = dyn_cast<ConstantInt>(Op)) {
         // For subtract, we don't need to sext the constant. We only put it in
         // SafeWrap because SafeWrap.size() is used elsewhere.
-        Constant *NewConst = (SafeWrap.contains(I) && i == 1 &&
+        // For cmp, we need to sign extend a constant appearing in either
+        // operand. For add, we should only sign extend the RHS.
+        Constant *NewConst = (SafeWrap.contains(I) &&
+                              (I->getOpcode() == Instruction::ICmp || i == 1) &&
                               I->getOpcode() != Instruction::Sub)
                                  ? ConstantExpr::getSExt(Const, ExtTy)
                                  : ConstantExpr::getZExt(Const, ExtTy);


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