forked from OSchip/llvm-project
69 lines
2.2 KiB
LLVM
69 lines
2.2 KiB
LLVM
; RUN: opt -gvn -S < %s | FileCheck %s
|
|
|
|
; C source:
|
|
;
|
|
; void f(int x) {
|
|
; if (x != 1)
|
|
; puts (x == 2 ? "a" : "b");
|
|
; for (;;) {
|
|
; puts("step 1");
|
|
; if (x == 2)
|
|
; continue;
|
|
; printf("step 2: %d\n", x);
|
|
; }
|
|
; }
|
|
;
|
|
; If we PRE %cmp3, CodeGenPrepare won't be able to sink the compare down to its
|
|
; uses, and we are forced to keep both %x and %cmp3 in registers in the loop.
|
|
;
|
|
; It is just as cheap to recompute the icmp against %x as it is to compare a
|
|
; GPR against 0. On x86-64, the br i1 %cmp3 becomes:
|
|
;
|
|
; testb %r12b, %r12b
|
|
; jne LBB0_3
|
|
;
|
|
; The sunk icmp is:
|
|
;
|
|
; cmpl $2, %ebx
|
|
; je LBB0_3
|
|
;
|
|
; This is just as good, and it doesn't require a separate register.
|
|
;
|
|
; CHECK-NOT: phi i1
|
|
|
|
@.str = private unnamed_addr constant [2 x i8] c"a\00", align 1
|
|
@.str1 = private unnamed_addr constant [2 x i8] c"b\00", align 1
|
|
@.str2 = private unnamed_addr constant [7 x i8] c"step 1\00", align 1
|
|
@.str3 = private unnamed_addr constant [12 x i8] c"step 2: %d\0A\00", align 1
|
|
|
|
define void @f(i32 %x) noreturn nounwind uwtable ssp {
|
|
entry:
|
|
%cmp = icmp eq i32 %x, 1
|
|
br i1 %cmp, label %for.cond.preheader, label %if.then
|
|
|
|
if.then: ; preds = %entry
|
|
%cmp1 = icmp eq i32 %x, 2
|
|
%cond = select i1 %cmp1, i8* getelementptr inbounds ([2 x i8]* @.str, i64 0, i64 0), i8* getelementptr inbounds ([2 x i8]* @.str1, i64 0, i64 0)
|
|
%call = tail call i32 @puts(i8* %cond) nounwind
|
|
br label %for.cond.preheader
|
|
|
|
for.cond.preheader: ; preds = %entry, %if.then
|
|
%cmp3 = icmp eq i32 %x, 2
|
|
br label %for.cond
|
|
|
|
for.cond: ; preds = %for.cond.backedge, %for.cond.preheader
|
|
%call2 = tail call i32 @puts(i8* getelementptr inbounds ([7 x i8]* @.str2, i64 0, i64 0)) nounwind
|
|
br i1 %cmp3, label %for.cond.backedge, label %if.end5
|
|
|
|
if.end5: ; preds = %for.cond
|
|
%call6 = tail call i32 (i8*, ...)* @printf(i8* getelementptr inbounds ([12 x i8]* @.str3, i64 0, i64 0), i32 %x) nounwind
|
|
br label %for.cond.backedge
|
|
|
|
for.cond.backedge: ; preds = %if.end5, %for.cond
|
|
br label %for.cond
|
|
}
|
|
|
|
declare i32 @puts(i8* nocapture) nounwind
|
|
|
|
declare i32 @printf(i8* nocapture, ...) nounwind
|