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75ce6b1096
The current BitPermutationSelector generates a code to build a value by tracking two types of bits: ConstZero and Variable. ConstZero means a bit we need to mask off and Variable is a bit we copy from an input value. This patch add third type of bits VariableKnownToBeZero caused by AssertZext node or zero-extending load node. VariableKnownToBeZero means a bit comes from an input value, but it is known to be already zero. So we do not need to mask them. VariableKnownToBeZero enhances flexibility to group bits, since we can avoid redundant masking for these bits. This patch also renames "HasZero" to "NeedMask" since now we may skip masking even when we have zeros (of type VariableKnownToBeZero). Differential Revision: https://reviews.llvm.org/D48025 llvm-svn: 344347
63 lines
1.7 KiB
LLVM
63 lines
1.7 KiB
LLVM
; RUN: llc -verify-machineinstrs -mtriple=powerpc64le-unknown-linux-gnu -mcpu=pwr8 < %s | FileCheck %s
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; RUN: llc -verify-machineinstrs -mtriple=powerpc64-unknown-linux-gnu -mcpu=pwr8 < %s | FileCheck %s
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; equivalent C code
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; struct s64 {
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; int a:5;
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; int b:16;
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; long c:42;
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; };
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; void bitfieldinsert64(struct s *p, unsigned short v) {
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; p->b = v;
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; }
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%struct.s64 = type { i64 }
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define void @bitfieldinsert64(%struct.s64* nocapture %p, i16 zeroext %v) {
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; CHECK-LABEL: @bitfieldinsert64
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; CHECK: ld [[REG1:[0-9]+]], 0(3)
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; CHECK-NEXT: rlwimi [[REG1]], 4, 5, 11, 26
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; CHECK-NEXT: std [[REG1]], 0(3)
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; CHECK-NEXT: blr
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entry:
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%0 = getelementptr inbounds %struct.s64, %struct.s64* %p, i64 0, i32 0
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%1 = zext i16 %v to i64
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%bf.load = load i64, i64* %0, align 8
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%bf.shl = shl nuw nsw i64 %1, 5
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%bf.clear = and i64 %bf.load, -2097121
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%bf.set = or i64 %bf.clear, %bf.shl
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store i64 %bf.set, i64* %0, align 8
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ret void
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}
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; bitfieldinsert32: Test for rlwimi
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; equivalent C code
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; struct s32 {
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; int a:8;
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; int b:16;
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; int c:8;
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; };
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; void bitfieldinsert32(struct s32 *p, unsigned int v) {
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; p->b = v;
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; }
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%struct.s32 = type { i32 }
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define void @bitfieldinsert32(%struct.s32* nocapture %p, i32 zeroext %v) {
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; CHECK-LABEL: @bitfieldinsert32
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; CHECK: lwz [[REG1:[0-9]+]], 0(3)
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; CHECK-NEXT: rlwimi [[REG1]], 4, 8, 8, 23
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; CHECK-NEXT: stw [[REG1]], 0(3)
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; CHECK-NEXT: blr
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entry:
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%0 = getelementptr inbounds %struct.s32, %struct.s32* %p, i64 0, i32 0
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%bf.load = load i32, i32* %0, align 4
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%bf.value = shl i32 %v, 8
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%bf.shl = and i32 %bf.value, 16776960
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%bf.clear = and i32 %bf.load, -16776961
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%bf.set = or i32 %bf.clear, %bf.shl
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store i32 %bf.set, i32* %0, align 4
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ret void
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}
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