| ; 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], [2 x i8]* @.str, i64 0, i64 0), i8* getelementptr inbounds ([2 x i8], [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], [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], [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 |
