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25279a5d22
Summary:
This patch adds instructions to the InstCombine worklist after they are properly inserted. This way we don't get `<badref>`s printed when logging added instructions.
It also adds a check in `Worklist::Add` that ensures that all added instructions have parents.
Simple test case that illustrates the difference when run with `--debug-only=instcombine`:
```
define i32 @test35(i32 %a, i32 %b) {
%1 = or i32 %a, 1135
%2 = or i32 %1, %b
ret i32 %2
}
```
Before this patch:
```
INSTCOMBINE ITERATION #1 on test35
IC: ADDING: 3 instrs to worklist
IC: Visiting: %1 = or i32 %a, 1135
IC: Visiting: %2 = or i32 %1, %b
IC: ADD: %2 = or i32 %a, %b
IC: Old = %3 = or i32 %1, %b
New = <badref> = or i32 %2, 1135
IC: ADD: <badref> = or i32 %2, 1135
...
```
With this patch:
```
INSTCOMBINE ITERATION #1 on test35
IC: ADDING: 3 instrs to worklist
IC: Visiting: %1 = or i32 %a, 1135
IC: Visiting: %2 = or i32 %1, %b
IC: ADD: %2 = or i32 %a, %b
IC: Old = %3 = or i32 %1, %b
New = <badref> = or i32 %2, 1135
IC: ADD: %3 = or i32 %2, 1135
...
```
Reviewers: fhahn, davide, spatel, foad, grosser, nikic
Reviewed By: nikic
Subscribers: nikic, lebedev.ri, hiraditya, llvm-commits
Tags: #llvm
Differential Revision: https://reviews.llvm.org/D71093
52 lines
1.6 KiB
LLVM
52 lines
1.6 KiB
LLVM
; RUN: opt < %s -instcombine -S | FileCheck %s
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; Remove an icmp by using its operand in the subsequent logic directly.
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define i8 @zext_or_icmp_icmp(i8 %a, i8 %b) {
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%mask = and i8 %a, 1
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%toBool1 = icmp eq i8 %mask, 0
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%toBool2 = icmp eq i8 %b, 0
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%bothCond = or i1 %toBool1, %toBool2
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%zext = zext i1 %bothCond to i8
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ret i8 %zext
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; CHECK-LABEL: zext_or_icmp_icmp(
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; CHECK-NEXT: %mask = and i8 %a, 1
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; CHECK-NEXT: %toBool2 = icmp eq i8 %b, 0
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; CHECK-NEXT: %toBool22 = zext i1 %toBool2 to i8
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; CHECK-NEXT: %1 = xor i8 %mask, 1
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; CHECK-NEXT: %zext3 = or i8 %1, %toBool22
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; CHECK-NEXT: ret i8 %zext
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}
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; Here, widening the or from i1 to i32 and removing one of the icmps would
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; widen an undef value (created by the out-of-range shift), increasing the
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; range of valid values for the return, so we can't do it.
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define i32 @dont_widen_undef() {
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entry:
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br label %block2
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block1:
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br label %block2
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block2:
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%m.011 = phi i32 [ 33, %entry ], [ 0, %block1 ]
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%cmp.i = icmp ugt i32 %m.011, 1
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%m.1.op = lshr i32 1, %m.011
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%sext.mask = and i32 %m.1.op, 65535
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%cmp115 = icmp ne i32 %sext.mask, 0
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%cmp1 = or i1 %cmp.i, %cmp115
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%conv2 = zext i1 %cmp1 to i32
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ret i32 %conv2
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; CHECK-LABEL: dont_widen_undef(
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; CHECK: %m.011 = phi i32 [ 33, %entry ], [ 0, %block1 ]
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; CHECK-NEXT: %cmp.i = icmp ugt i32 %m.011, 1
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; CHECK-NEXT: %m.1.op = lshr i32 1, %m.011
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; CHECK-NEXT: %sext.mask = and i32 %m.1.op, 65535
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; CHECK-NEXT: %cmp115 = icmp ne i32 %sext.mask, 0
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; CHECK-NEXT: %cmp1 = or i1 %cmp.i, %cmp115
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; CHECK-NEXT: %conv2 = zext i1 %cmp1 to i32
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; CHECK-NEXT: ret i32 %conv2
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}
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