a105877646
The idea behind this canonicalization is that it allows us to handle less patterns, because we know that some will be canonicalized away. This is indeed very useful to e.g. know that constants are always on the right. However, this is only useful if the canonicalization is actually reliable. This is the case for constants, but not for arguments: Moving these to the right makes it look like the "more complex" expression is guaranteed to be on the left, but this is not actually the case in practice. It fails as soon as you replace the argument with another instruction. The end result is that it looks like things correctly work in tests, while they actually don't. We use the "thwart complexity-based canonicalization" trick to handle this in tests, but it's often a challenge for new contributors to get this right, and based on the regressions this PR originally exposed, we clearly don't get this right in many cases. For this reason, I think that it's better to remove this complexity canonicalization. It will make it much easier to write tests for commuted cases and make sure that they are handled.
115 lines
3.9 KiB
LLVM
115 lines
3.9 KiB
LLVM
; NOTE: Assertions have been autogenerated by utils/update_test_checks.py
|
|
; RUN: opt < %s -passes=reassociate,instcombine -S | FileCheck %s
|
|
|
|
define float @test1(float %A, float %B) {
|
|
; CHECK-LABEL: @test1(
|
|
; CHECK-NEXT: [[W:%.*]] = fadd float [[B:%.*]], 5.000000e+00
|
|
; CHECK-NEXT: [[X:%.*]] = fadd float [[A:%.*]], -7.000000e+00
|
|
; CHECK-NEXT: [[Y:%.*]] = fsub float [[X]], [[W]]
|
|
; CHECK-NEXT: [[Z:%.*]] = fadd float [[Y]], 1.200000e+01
|
|
; CHECK-NEXT: ret float [[Z]]
|
|
;
|
|
%W = fadd float 5.0, %B
|
|
%X = fadd float -7.0, %A
|
|
%Y = fsub float %X, %W
|
|
%Z = fadd float %Y, 12.0
|
|
ret float %Z
|
|
}
|
|
|
|
; With sub reassociation, constant folding can eliminate all of the constants.
|
|
define float @test2(float %A, float %B) {
|
|
; CHECK-LABEL: @test2(
|
|
; CHECK-NEXT: [[Z:%.*]] = fsub fast float [[A:%.*]], [[B:%.*]]
|
|
; CHECK-NEXT: ret float [[Z]]
|
|
;
|
|
%W = fadd fast float %B, 5.000000e+00
|
|
%X = fadd fast float %A, -7.000000e+00
|
|
%Y = fsub fast float %X, %W
|
|
%Z = fadd fast float %Y, 1.200000e+01
|
|
ret float %Z
|
|
}
|
|
|
|
; Check again using minimal subset of FMF.
|
|
; Both 'reassoc' and 'nsz' are required.
|
|
define float @test2_minimal(float %A, float %B) {
|
|
; CHECK-LABEL: @test2_minimal(
|
|
; CHECK-NEXT: [[Z:%.*]] = fsub reassoc nsz float [[A:%.*]], [[B:%.*]]
|
|
; CHECK-NEXT: ret float [[Z]]
|
|
;
|
|
%W = fadd reassoc nsz float %B, 5.000000e+00
|
|
%X = fadd reassoc nsz float %A, -7.000000e+00
|
|
%Y = fsub reassoc nsz float %X, %W
|
|
%Z = fadd reassoc nsz float %Y, 1.200000e+01
|
|
ret float %Z
|
|
}
|
|
|
|
; Verify the fold is not done with only 'reassoc' ('nsz' is required).
|
|
define float @test2_reassoc(float %A, float %B) {
|
|
; CHECK-LABEL: @test2_reassoc(
|
|
; CHECK-NEXT: [[W:%.*]] = fadd reassoc float [[B:%.*]], 5.000000e+00
|
|
; CHECK-NEXT: [[X:%.*]] = fadd reassoc float [[A:%.*]], -7.000000e+00
|
|
; CHECK-NEXT: [[Y:%.*]] = fsub reassoc float [[X]], [[W]]
|
|
; CHECK-NEXT: [[Z:%.*]] = fadd reassoc float [[Y]], 1.200000e+01
|
|
; CHECK-NEXT: ret float [[Z]]
|
|
;
|
|
%W = fadd reassoc float %B, 5.000000e+00
|
|
%X = fadd reassoc float %A, -7.000000e+00
|
|
%Y = fsub reassoc float %X, %W
|
|
%Z = fadd reassoc float %Y, 1.200000e+01
|
|
ret float %Z
|
|
}
|
|
|
|
define float @test3(float %A, float %B, float %C, float %D) {
|
|
; CHECK-LABEL: @test3(
|
|
; CHECK-NEXT: [[M:%.*]] = fadd float [[A:%.*]], 1.200000e+01
|
|
; CHECK-NEXT: [[N:%.*]] = fadd float [[M]], [[B:%.*]]
|
|
; CHECK-NEXT: [[O:%.*]] = fadd float [[N]], [[C:%.*]]
|
|
; CHECK-NEXT: [[P:%.*]] = fsub float [[D:%.*]], [[O]]
|
|
; CHECK-NEXT: [[Q:%.*]] = fadd float [[P]], 1.200000e+01
|
|
; CHECK-NEXT: ret float [[Q]]
|
|
;
|
|
%M = fadd float %A, 1.200000e+01
|
|
%N = fadd float %M, %B
|
|
%O = fadd float %N, %C
|
|
%P = fsub float %D, %O
|
|
%Q = fadd float %P, 1.200000e+01
|
|
ret float %Q
|
|
}
|
|
|
|
; With sub reassociation, constant folding can eliminate the two 12 constants.
|
|
|
|
define float @test4(float %A, float %B, float %C, float %D) {
|
|
; CHECK-LABEL: @test4(
|
|
; CHECK-NEXT: [[TMP1:%.*]] = fadd fast float [[B:%.*]], [[A:%.*]]
|
|
; CHECK-NEXT: [[TMP2:%.*]] = fadd fast float [[C:%.*]], [[TMP1]]
|
|
; CHECK-NEXT: [[Q:%.*]] = fsub fast float [[D:%.*]], [[TMP2]]
|
|
; CHECK-NEXT: ret float [[Q]]
|
|
;
|
|
%M = fadd fast float 1.200000e+01, %A
|
|
%N = fadd fast float %M, %B
|
|
%O = fadd fast float %N, %C
|
|
%P = fsub fast float %D, %O
|
|
%Q = fadd fast float 1.200000e+01, %P
|
|
ret float %Q
|
|
}
|
|
|
|
; Check again using minimal subset of FMF.
|
|
|
|
define float @test4_reassoc(float %A, float %B, float %C, float %D) {
|
|
; CHECK-LABEL: @test4_reassoc(
|
|
; CHECK-NEXT: [[M:%.*]] = fadd reassoc float [[A:%.*]], 1.200000e+01
|
|
; CHECK-NEXT: [[N:%.*]] = fadd reassoc float [[M]], [[B:%.*]]
|
|
; CHECK-NEXT: [[O:%.*]] = fadd reassoc float [[N]], [[C:%.*]]
|
|
; CHECK-NEXT: [[P:%.*]] = fsub reassoc float [[D:%.*]], [[O]]
|
|
; CHECK-NEXT: [[Q:%.*]] = fadd reassoc float [[P]], 1.200000e+01
|
|
; CHECK-NEXT: ret float [[Q]]
|
|
;
|
|
%M = fadd reassoc float 1.200000e+01, %A
|
|
%N = fadd reassoc float %M, %B
|
|
%O = fadd reassoc float %N, %C
|
|
%P = fsub reassoc float %D, %O
|
|
%Q = fadd reassoc float 1.200000e+01, %P
|
|
ret float %Q
|
|
}
|
|
|