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Craig Topper 124ae55576 [X86] Prevent folding loads with 64-bit ANDs with immediates that fit in 32-bits.
Prefer to use the 32-bit AND with immediate instead.

Primarily I'm doing this to ensure that immediates created by shrinkAndImmediate will always get absorbed into the AND. But I do believe this would be a reduction in the number of uops that need to execute. Ideally we should shrink the 'and' and the 'load' during DAG combine to re-enable the fold.

Fixes PR37063.

llvm-svn: 329667
2018-04-10 03:44:15 +00:00

32 lines
851 B
LLVM

; NOTE: Assertions have been autogenerated by utils/update_llc_test_checks.py
; RUN: llc < %s -mtriple=x86_64-unknown-unknown | FileCheck %s
declare void @bar()
define void @foo(i64*) {
; CHECK-LABEL: foo:
; CHECK: # %bb.0: # %start
; CHECK-NEXT: movq (%rdi), %rax
; CHECK-NEXT: andl $-2, %eax
; CHECK-NEXT: cmpq $4, %rax
; CHECK-NEXT: jne .LBB0_2
; CHECK-NEXT: # %bb.1: # %bb1
; CHECK-NEXT: retq
; CHECK-NEXT: .LBB0_2: # %bb2.i
; CHECK-NEXT: jmp bar # TAILCALL
start:
%1 = load i64, i64* %0, align 8, !range !0
%2 = and i64 %1, 6
%3 = icmp eq i64 %2, 4
br i1 %3, label %bb1, label %bb2.i
bb1: ; preds = %bb2.i, %start
ret void
bb2.i: ; preds = %start
tail call fastcc void @bar()
br label %bb1
}
!0 = !{i64 0, i64 6}