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Pre-commit test cases for (sra (load)) -> (sextload) folds. NFC 

Add test case to show missing folds for (sra (load)) -> (sextload).

Differential Revision: https://reviews.llvm.org/D116929
This commit is contained in:
Bjorn Pettersson 2022-01-10 11:32:08 +01:00
parent 99e8e17313
commit 354b2c36ee
1 changed files with 107 additions and 0 deletions
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107
llvm/test/CodeGen/X86/combine-sra-load.ll Normal file
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; NOTE: Assertions have been autogenerated by utils/update_llc_test_checks.py
; RUN: llc < %s -mtriple=x86_64-unknown-unknown | FileCheck %s --check-prefix=CHECK
; FIXME: fold (sra (load i32), 16)) -> (sextload i16)
define i32 @sra_half(i32* %p) {
; CHECK-LABEL: sra_half:
; CHECK: # %bb.0:
; CHECK-NEXT: movl (%rdi), %eax
; CHECK-NEXT: sarl $16, %eax
; CHECK-NEXT: retq
%load = load i32, i32* %p
%shift = ashr i32 %load, 16
ret i32 %shift
}
; Vector version not folded.
define <4 x i32> @sra_half_vec(<4 x i32>* %p) {
; CHECK-LABEL: sra_half_vec:
; CHECK: # %bb.0:
; CHECK-NEXT: movdqa (%rdi), %xmm0
; CHECK-NEXT: psrad $16, %xmm0
; CHECK-NEXT: retq
%load = load <4 x i32>, <4 x i32>* %p
%shift = ashr <4 x i32> %load, <i32 16, i32 16, i32 16, i32 16>
ret <4 x i32> %shift
}
; FIXME: fold (sra (load i64), 48)) -> (sextload i16)
define i64 @sra_large_shift(i64* %r) {
; CHECK-LABEL: sra_large_shift:
; CHECK: # %bb.0:
; CHECK-NEXT: movq (%rdi), %rax
; CHECK-NEXT: sarq $48, %rax
; CHECK-NEXT: retq
%t0 = load i64, i64* %r
%conv = ashr i64 %t0, 48
ret i64 %conv
}
; Negative test, no fold expected.
define i32 @sra_small_shift(i32* %p) {
; CHECK-LABEL: sra_small_shift:
; CHECK: # %bb.0:
; CHECK-NEXT: movl (%rdi), %eax
; CHECK-NEXT: sarl $8, %eax
; CHECK-NEXT: retq
%load = load i32, i32* %p
%shift = ashr i32 %load, 8
ret i32 %shift
}
; This should be folded to a zextload.
define i32 @sra_of_zextload(i16* %p) {
; CHECK-LABEL: sra_of_zextload:
; CHECK: # %bb.0:
; CHECK-NEXT: movzbl 1(%rdi), %eax
; CHECK-NEXT: retq
%load = load i16, i16* %p
%zext = zext i16 %load to i32
%shift = ashr i32 %zext, 8
ret i32 %shift
}
; FIXME: fold (sra (sextload i16 to i32), 8) -> (sextload i8)
define i32 @sra_of_sextload(i16* %p) {
; CHECK-LABEL: sra_of_sextload:
; CHECK: # %bb.0:
; CHECK-NEXT: movswl (%rdi), %eax
; CHECK-NEXT: sarl $8, %eax
; CHECK-NEXT: retq
%load = load i16, i16* %p
%sext = sext i16 %load to i32
%shift = ashr i32 %sext, 8
ret i32 %shift
}
; Negative test. If the shift amount is larger than the memory type then
; we're not accessing any of the loaded bytes (only the extended bits). So the
; shift is expected to remain.
define i32 @sra_of_sextload_no_fold(i16* %p) {
; CHECK-LABEL: sra_of_sextload_no_fold:
; CHECK: # %bb.0:
; CHECK-NEXT: movswl (%rdi), %eax
; CHECK-NEXT: sarl $16, %eax
; CHECK-NEXT: retq
%load = load i16, i16* %p
%sext = sext i16 %load to i32
%shift = ashr i32 %sext, 16
ret i32 %shift
}
; FIXME: Fold even if SRA has multiple uses.
define i32 @sra_to_sextload_multiple_sra_uses(i32* %p) {
; CHECK-LABEL: sra_to_sextload_multiple_sra_uses:
; CHECK: # %bb.0:
; CHECK-NEXT: movl (%rdi), %ecx
; CHECK-NEXT: sarl $16, %ecx
; CHECK-NEXT: movl %ecx, %eax
; CHECK-NEXT: xorl $6, %eax
; CHECK-NEXT: orl %ecx, %eax
; CHECK-NEXT: retq
%load = load i32, i32* %p
%shift = ashr i32 %load, 16
%use1 = xor i32 %shift, 6
%use2 = or i32 %shift, %use1
ret i32 %use2
}