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llvm-mirror/test/CodeGen/X86/shift-pair.ll
Simon Pilgrim d654e7d40c [X86] Handle COPYs of physregs better (regalloc hints)
Enable enableMultipleCopyHints() on X86.

Original Patch by @jonpa:

While enabling the mischeduler for SystemZ, it was discovered that for some reason a test needed one extra seemingly needless COPY (test/CodeGen/SystemZ/call-03.ll). The handling for that is resulted in this patch, which improves the register coalescing by providing not just one copy hint, but a sorted list of copy hints. On SystemZ, this gives ~12500 less register moves on SPEC, as well as marginally less spilling.

Instead of improving just the SystemZ backend, the improvement has been implemented in common-code (calculateSpillWeightAndHint(). This gives a lot of test failures, but since this should be a general improvement I hope that the involved targets will help and review the test updates.

Differential Revision: https://reviews.llvm.org/D38128

llvm-svn: 342578
2018-09-19 18:59:08 +00:00

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384 B
LLVM

; NOTE: Assertions have been autogenerated by utils/update_llc_test_checks.py
; RUN: llc < %s -mtriple=x86_64-- | FileCheck %s
define i64 @test(i64 %A) {
; CHECK-LABEL: test:
; CHECK: # %bb.0:
; CHECK-NEXT: movq %rdi, %rax
; CHECK-NEXT: shrq $54, %rax
; CHECK-NEXT: andl $-4, %eax
; CHECK-NEXT: retq
%B = lshr i64 %A, 56
%C = shl i64 %B, 2
ret i64 %C
}