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[AArch64] CondOpt pass is missing FCMP instructions when searching backward for

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a CMP which defines the flags used by B.CC.

http://reviews.llvm.org/D6047
Patch by Zhaoshi Zheng <zhaoshiz@codeaurora.org>!

llvm-svn: 220961
This commit is contained in:
Chad Rosier 2014-10-31 15:17:36 +00:00
parent 3e03fb9d20
commit 9bc5bd5f9a
2 changed files with 75 additions and 0 deletions
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11
lib/Target/AArch64/AArch64ConditionOptimizer.cpp
View File

@ -155,6 +155,17 @@ MachineInstr *AArch64ConditionOptimizer::findSuitableCompare(
case AArch64::ADDSXri:
return I;
// Prevent false positive case like:
// cmp w19, #0
// cinc w0, w19, gt
// ...
// fcmp d8, #0.0
// b.gt .LBB0_5
case AArch64::FCMPDri:
case AArch64::FCMPSri:
case AArch64::FCMPESri:
case AArch64::FCMPEDri:
case AArch64::SUBSWrr:
case AArch64::SUBSXrr:
case AArch64::ADDSWrr:

64
test/CodeGen/AArch64/combine-comparisons-by-cse.ll
View File

@ -347,3 +347,67 @@ return: ; preds = %if.end, %land.lhs.t
%retval.0 = phi i32 [ 0, %if.end ], [ 123, %land.lhs.true ]
ret i32 %retval.0
}
; Test in the following case, we don't hit 'cmp' and trigger a false positive
; cmp w19, #0
; cinc w0, w19, gt
; ...
; fcmp d8, #0.0
; b.gt .LBB0_5
define i32 @fcmpri(i32 %argc, i8** nocapture readonly %argv) {
; CHECK-LABEL: fcmpri:
; CHECK: cmp w0, #2
; CHECK: b.lt .LBB9_3
; CHECK-NOT: cmp w0, #1
; CHECK-NOT: b.le .LBB9_3
; CHECK-LABEL-DAG: .LBB9_3
; CHECK: cmp w19, #0
; CHECK: fcmp d8, #0.0
; CHECK: b.gt .LBB9_5
; CHECK-NOT: cmp w19, #1
; CHECK-NOT: b.ge .LBB9_5
entry:
%cmp = icmp sgt i32 %argc, 1
br i1 %cmp, label %land.lhs.true, label %if.end
land.lhs.true: ; preds = %entry
%arrayidx = getelementptr inbounds i8** %argv, i64 1
%0 = load i8** %arrayidx, align 8
%cmp1 = icmp eq i8* %0, null
br i1 %cmp1, label %if.end, label %return
if.end: ; preds = %land.lhs.true, %entry
%call = call i32 @zoo(i32 1)
%call2 = call double @yoo(i32 -1)
%cmp4 = icmp sgt i32 %call, 0
%add = zext i1 %cmp4 to i32
%cond = add nsw i32 %add, %call
%call7 = call i32 @xoo(i32 %cond, i32 2)
%cmp9 = fcmp ogt double %call2, 0.000000e+00
br i1 %cmp9, label %cond.end14, label %cond.false12
cond.false12: ; preds = %if.end
%sub = fadd fast double %call2, -1.000000e+00
br label %cond.end14
cond.end14: ; preds = %if.end, %cond.false12
%cond15 = phi double [ %sub, %cond.false12 ], [ %call2, %if.end ]
%call16 = call i32 @woo(double %cond15, double -2.000000e+00)
br label %return
return: ; preds = %land.lhs.true, %cond.end14
%retval.0 = phi i32 [ 4, %cond.end14 ], [ 3, %land.lhs.true ]
ret i32 %retval.0
}
declare i32 @zoo(i32)
declare double @yoo(i32)
declare i32 @xoo(i32, i32)
declare i32 @woo(double, double)