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llvm-mirror/test/CodeGen/X86/immediate_merging64.ll
Sanjay Patel 36b572f1e0 [x86] Allow merging multiple instances of an immediate within a basic block for code size savings, for 64-bit constants.
This patch handles 64-bit constants which can be encoded as 32-bit immediates.

It extends the functionality added by https://reviews.llvm.org/D11363 for 32-bit constants to 64-bit constants.

Patch by Sunita Marathe!

Differential Revision: https://reviews.llvm.org/D23391

llvm-svn: 278857
2016-08-16 21:35:16 +00:00

39 lines
1.2 KiB
LLVM

; NOTE: Assertions have been autogenerated by utils/update_test_checks.py
; RUN: llc < %s -mtriple=x86_64-unknown-linux-gnu | FileCheck %s
; Check that multiple instances of 64-bit constants encodable as
; 32-bit immediates are merged for code size savings.
; Immediates with multiple users should not be pulled into instructions when
; optimizing for code size.
define i1 @imm_multiple_users(i64 %a, i64* %b) optsize {
; CHECK-LABEL: imm_multiple_users:
; CHECK: # BB#0:
; CHECK-NEXT: movq $-1, %rax
; CHECK-NEXT: movq %rax, (%rsi)
; CHECK-NEXT: cmpq %rax, %rdi
; CHECK-NEXT: sete %al
; CHECK-NEXT: retq
;
store i64 -1, i64* %b, align 8
%cmp = icmp eq i64 %a, -1
ret i1 %cmp
}
declare void @llvm.memset.p0i8.i64(i8* nocapture, i8, i64, i32, i1)
; Inlined memsets requiring multiple same-sized stores should be lowered using
; the register, rather than immediate, form of stores when optimizing for
; code size.
define void @memset_zero(i8* noalias nocapture %D) optsize {
; CHECK-LABEL: memset_zero:
; CHECK: # BB#0:
; CHECK-NEXT: xorl %eax, %eax
; CHECK-NEXT: movq %rax, 7(%rdi)
; CHECK-NEXT: movq %rax, (%rdi)
; CHECK-NEXT: retq
;
tail call void @llvm.memset.p0i8.i64(i8* %D, i8 0, i64 15, i32 1, i1 false)
ret void
}