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| author |   Simon Pilgrim <llvm-dev@redking.me.uk> | 2020-01-13 11:07:53 +0000 |
|---|---|---|
| committer | Simon Pilgrim <llvm-dev@redking.me.uk> | 2020-01-13 11:08:12 +0000 |
| commit | 8f49204f26ea8856b870d4c2344b98f4b706bea0 (patch) | |
| tree | 70fb38f062d77cd099787b5d02a25f7e5fb1b920 /llvm/test/CodeGen/AArch64/hoist-and-by-const-from-shl-in-eqcmp-zero.ll | |
| parent | [X86] Fix MSVC "truncation from 'int' to 'bool'" warning. NFCI. (diff) | |
| download | llvm-project-8f49204f26ea8856b870d4c2344b98f4b706bea0.tar.gz llvm-project-8f49204f26ea8856b870d4c2344b98f4b706bea0.tar.bz2 llvm-project-8f49204f26ea8856b870d4c2344b98f4b706bea0.zip | |
[SelectionDAG] ComputeKnownBits - minimum leading/trailing zero bits in LSHR/SHL (PR44526)
As detailed in https://blog.regehr.org/archives/1709 we don't make use of the known leading/trailing zeros for shifted values in cases where we don't know the shift amount value.
This patch adds support to SelectionDAG::ComputeKnownBits to use KnownBits::countMinTrailingZeros and countMinLeadingZeros to set the minimum guaranteed leading/trailing known zero bits.
Differential Revision: https://reviews.llvm.org/D72573
Diffstat (limited to 'llvm/test/CodeGen/AArch64/hoist-and-by-const-from-shl-in-eqcmp-zero.ll')
| -rw-r--r-- | llvm/test/CodeGen/AArch64/hoist-and-by-const-from-shl-in-eqcmp-zero.ll | 4 |
1 files changed, 2 insertions, 2 deletions
diff --git a/llvm/test/CodeGen/AArch64/hoist-and-by-const-from-shl-in-eqcmp-zero.ll b/llvm/test/CodeGen/AArch64/hoist-and-by-const-from-shl-in-eqcmp-zero.ll index 90e007cbd775..2a5bfeb3082e 100644 --- a/llvm/test/CodeGen/AArch64/hoist-and-by-const-from-shl-in-eqcmp-zero.ll +++ b/llvm/test/CodeGen/AArch64/hoist-and-by-const-from-shl-in-eqcmp-zero.ll @@ -274,7 +274,7 @@ define i1 @scalar_i8_signbit_ne(i8 %x, i8 %y) nounwind { ; CHECK-NEXT: and w8, w0, #0xff ; CHECK-NEXT: // kill: def $w1 killed $w1 def $x1 ; CHECK-NEXT: lsr w8, w8, w1 -; CHECK-NEXT: ubfx w0, w8, #7, #1 +; CHECK-NEXT: lsr w0, w8, #7 ; CHECK-NEXT: ret %t0 = shl i8 128, %y %t1 = and i8 %t0, %x @@ -344,7 +344,7 @@ define i1 @scalar_i8_signbit_eq_with_nonzero(i8 %x, i8 %y) nounwind { ; CHECK-NEXT: // kill: def $w1 killed $w1 def $x1 ; CHECK-NEXT: lsl w8, w8, w1 ; CHECK-NEXT: and w8, w8, w0 -; CHECK-NEXT: and w8, w8, #0xff +; CHECK-NEXT: and w8, w8, #0x80 ; CHECK-NEXT: cmp w8, #1 // =1 ; CHECK-NEXT: cset w0, eq ; CHECK-NEXT: ret |