diff options
| -rw-r--r-- | llvm/lib/CodeGen/CodeGenPrepare.cpp | 11 | ||||
| -rw-r--r-- | llvm/test/Transforms/CodeGenPrepare/ARM/overflow-intrinsics.ll | 56 |
2 files changed, 67 insertions, 0 deletions
diff --git a/llvm/lib/CodeGen/CodeGenPrepare.cpp b/llvm/lib/CodeGen/CodeGenPrepare.cpp index 80335f55c77..af1b65253f8 100644 --- a/llvm/lib/CodeGen/CodeGenPrepare.cpp +++ b/llvm/lib/CodeGen/CodeGenPrepare.cpp @@ -1180,6 +1180,17 @@ static bool replaceMathCmpWithIntrinsic(BinaryOperator *BO, CmpInst *Cmp, bool MathDominates = DT.dominates(BO, Cmp); if (!MathDominates && !DT.dominates(Cmp, BO)) return false; + + // Check that the insertion doesn't create a value that is live across more + // than two blocks, so to minimise the increase in register pressure. + if (BO->getParent() != Cmp->getParent()) { + BasicBlock *Dominator = MathDominates ? BO->getParent() : Cmp->getParent(); + BasicBlock *Dominated = MathDominates ? Cmp->getParent() : BO->getParent(); + auto Successors = successors(Dominator); + if (llvm::find(Successors, Dominated) == Successors.end()) + return false; + } + InsertPt = MathDominates ? cast<Instruction>(BO) : cast<Instruction>(Cmp); } diff --git a/llvm/test/Transforms/CodeGenPrepare/ARM/overflow-intrinsics.ll b/llvm/test/Transforms/CodeGenPrepare/ARM/overflow-intrinsics.ll new file mode 100644 index 00000000000..3fbc2133141 --- /dev/null +++ b/llvm/test/Transforms/CodeGenPrepare/ARM/overflow-intrinsics.ll @@ -0,0 +1,56 @@ +; RUN: opt -codegenprepare -S < %s | FileCheck %s + +target datalayout = "e-m:e-p:32:32-i64:64-v128:64:128-a:0:32-n32-S64" +target triple = "thumbv8m.main-arm-none-eabi" + +; CHECK-LABEL: uadd_overflow_too_far_cmp_dom +; CHECK-NOT: with.overflow.i32 +define i32 @uadd_overflow_too_far_cmp_dom(i32 %arg0) { +entry: + %cmp = icmp ne i32 %arg0, 0 + br i1 %cmp, label %if.else, label %if.then + +if.then: + call void @foo() + br label %exit + +if.else: + call void @bar() + br label %if.end + +if.end: + %dec = add nsw i32 %arg0, -1 + br label %exit + +exit: + %res = phi i32 [ %arg0, %if.then ], [ %dec, %if.end ] + ret i32 %res +} + +; CHECK-LABEL: uadd_overflow_too_far_math_dom +; CHECK-NOT: with.overflow.i32 +define i32 @uadd_overflow_too_far_math_dom(i32 %arg0, i32 %arg1) { +entry: + %dec = add nsw i32 %arg0, -1 + %cmp = icmp ugt i32 %arg0, 1 + br i1 %cmp, label %if.else, label %if.then + +if.then: + call void @foo() + br label %if.end + +if.else: + call void @bar() + br label %if.end + +if.end: + %cmp.i.i = icmp ne i32 %arg0, 0 + %tobool = zext i1 %cmp.i.i to i32 + br label %exit + +exit: + ret i32 %tobool +} + +declare void @foo() +declare void @bar() |
