diff options
Diffstat (limited to 'llvm/test/CodeGen/Hexagon')
| -rw-r--r-- | llvm/test/CodeGen/Hexagon/undo-dag-shift.ll | 59 |
1 files changed, 59 insertions, 0 deletions
diff --git a/llvm/test/CodeGen/Hexagon/undo-dag-shift.ll b/llvm/test/CodeGen/Hexagon/undo-dag-shift.ll new file mode 100644 index 00000000000..c1ab5d73f5c --- /dev/null +++ b/llvm/test/CodeGen/Hexagon/undo-dag-shift.ll @@ -0,0 +1,59 @@ +; RUN: llc -march=hexagon < %s | FileCheck %s + +; DAG combiner folds sequences of shifts, which can sometimes obscure +; optimization opportunities. For example +; +; unsigned int c(unsigned int b, unsigned int *a) { +; unsigned int bitidx = b >> 5; +; return a[bitidx]; +; } +; +; produces +; (add x (shl (srl y 5) 2)) +; which is then folded into +; (add x (and (srl y 3) 1FFFFFFC)) +; +; That results in a constant-extended and: +; r0 = and(##536870908,lsr(r0,#3)) +; r0 = memw(r1+r0<<#0) +; whereas +; r0 = lsr(r0,#5) +; r0 = memw(r1+r0<<#2) +; is more desirable. + +target triple = "hexagon" + +; CHECK-LABEL: load_0 +; CHECK: memw(r{{[0-9]+}}+r{{[0-9]}}<<#2) +define i32 @load_0(i32 %b, i32* nocapture readonly %a) #0 { +entry: + %shr = lshr i32 %b, 5 + %arrayidx = getelementptr inbounds i32, i32* %a, i32 %shr + %0 = load i32, i32* %arrayidx, align 4 + ret i32 %0 +} + +; This would require r0<<#3, which is not legal. +; CHECK-LABEL: load_1 +; CHECK: memw(r{{[0-9]+}}+r{{[0-9]}}<<#0) +define i32 @load_1(i32 %b, [3 x i32]* nocapture readonly %a) #0 { +entry: + %shr = lshr i32 %b, 5 + %arrayidx = getelementptr inbounds [3 x i32], [3 x i32]* %a, i32 %shr, i32 0 + %0 = load i32, i32* %arrayidx, align 4 + ret i32 %0 +} + +; CHECK-LABEL: store_0 +; CHECK: memw(r{{[0-9]+}}+r{{[0-9]}}<<#2) +define void @store_0(i32 %b, i32* nocapture %a, i32 %v) #1 { +entry: + %shr = lshr i32 %b, 5 + %arrayidx = getelementptr inbounds i32, i32* %a, i32 %shr + store i32 %v, i32* %arrayidx, align 4 + ret void +} + +attributes #0 = { norecurse nounwind readonly "target-cpu"="hexagonv60" "target-features"="-hvx,-hvx-double,-long-calls" } +attributes #1 = { norecurse nounwind "target-cpu"="hexagonv60" "target-features"="-hvx,-hvx-double,-long-calls" } + |
