lebedev.ri commandeered this revision.
lebedev.ri edited reviewers, added: nikic; removed: lebedev.ri.
lebedev.ri added a comment.
@mstorsjo please can you be more specific what kind of tests are starting to
fail?
Do those tests just check that the code compiled into an identical assembly?
I reduced `vc1_block-aarch64.c`, and got:
; ModuleID = 'input.ll'
source_filename = "vc1_block-aarch64.c"
target datalayout = "e-m:w-p:64:64-i32:32-i64:64-i128:128-n32:64-S128"
target triple = "aarch64-w64-windows-gnu"
define i1 @barney(i8 %arg, i8 %arg9) {
bb:
%tmp = sext i8 %arg to i32
%tmp10 = icmp slt i32 %tmp, 0
%tmp11 = sub nsw i32 0, %tmp
%tmp12 = select i1 %tmp10, i32 %tmp11, i32 %tmp
%tmp13 = shl nuw nsw i32 %tmp12, 1
%tmp14 = zext i8 %arg9 to i32
%tmp15 = add nuw nsw i32 %tmp13, %tmp14
%tmp16 = icmp slt i32 %tmp15, 2
ret i1 %tmp16
}
declare i32 @eggs()
which used to get optimized into
; ModuleID = '<stdin>'
source_filename = "vc1_block-aarch64.c"
target datalayout = "e-m:w-p:64:64-i32:32-i64:64-i128:128-n32:64-S128"
target triple = "aarch64-w64-windows-gnu"
define i1 @barney(i8 %arg, i8 %arg9) {
bb:
%tmp = sext i8 %arg to i32
%tmp10 = icmp slt i32 %tmp, 0
%tmp11 = sub nsw i32 0, %tmp
%tmp12 = select i1 %tmp10, i32 %tmp11, i32 %tmp
%tmp13 = shl nuw nsw i32 %tmp12, 1
%tmp14 = zext i8 %arg9 to i32
%tmp15 = add nuw nsw i32 %tmp13, %tmp14
%tmp16 = icmp slt i32 %tmp15, 2
ret i1 %tmp16
}
declare i32 @eggs()
and is now optimized into
; ModuleID = '<stdin>'
source_filename = "vc1_block-aarch64.c"
target datalayout = "e-m:w-p:64:64-i32:32-i64:64-i128:128-n32:64-S128"
target triple = "aarch64-w64-windows-gnu"
define i1 @barney(i8 %arg, i8 %arg9) {
bb:
%tmp = sext i8 %arg to i32
%0 = call i32 @llvm.abs.i32(i32 %tmp, i1 true)
%tmp13 = shl nuw nsw i32 %0, 1
%tmp14 = zext i8 %arg9 to i32
%tmp15 = add nuw nsw i32 %tmp13, %tmp14
%tmp16 = icmp ult i32 %tmp15, 2
ret i1 %tmp16
}
declare i32 @eggs()
; Function Attrs: nofree nosync nounwind readnone speculatable willreturn
declare i32 @llvm.abs.i32(i32, i1 immarg) #0
attributes #0 = { nofree nosync nounwind readnone speculatable willreturn }
which is not a miscompile:
$ /repositories/alive2/build-Clang-release/alive-tv old.ll new.ll
----------------------------------------
define i1 @barney(i8 %arg, i8 %arg9) {
%bb:
%tmp = sext i8 %arg to i32
%tmp10 = icmp slt i32 %tmp, 0
%tmp11 = sub nsw i32 0, %tmp
%tmp12 = select i1 %tmp10, i32 %tmp11, i32 %tmp
%tmp13 = shl nsw nuw i32 %tmp12, 1
%tmp14 = zext i8 %arg9 to i32
%tmp15 = add nsw nuw i32 %tmp13, %tmp14
%tmp16 = icmp slt i32 %tmp15, 2
ret i1 %tmp16
}
=>
define i1 @barney(i8 %arg, i8 %arg9) {
%bb:
%tmp = sext i8 %arg to i32
%0 = abs i32 %tmp, 1
%tmp13 = shl nsw nuw i32 %0, 1
%tmp14 = zext i8 %arg9 to i32
%tmp15 = add nsw nuw i32 %tmp13, %tmp14
%tmp16 = icmp ult i32 %tmp15, 2
ret i1 %tmp16
}
Transformation seems to be correct!
Summary:
1 correct transformations
0 incorrect transformations
0 Alive2 errors
The original assembly was:
.text
.file "vc1_block-aarch64.c"
.def barney;
.scl 2;
.type 32;
.endef
.globl barney // -- Begin function barney
.p2align 2
barney: // @barney
// %bb.0: // %bb
sxtb w8, w0
cmp w8, #0 // =0
cneg w8, w8, mi
lsl w8, w8, #1
add w8, w8, w1, uxtb
cmp w8, #2 // =2
cset w0, lt
ret
// -- End function
and new one is
.text
.file "vc1_block-aarch64.c"
.def barney;
.scl 2;
.type 32;
.endef
.globl barney // -- Begin function barney
.p2align 2
barney: // @barney
// %bb.0: // %bb
sxtb w8, w0
cmp w8, #0 // =0
cneg w8, w8, mi
lsl w8, w8, #1
add w8, w8, w1, uxtb
cmp w8, #2 // =2
cset w0, lo
ret
// -- End function
with diff being
$ diff old.s new.s
17c17
< cset w0, lt
---
> cset w0, lo
CHANGES SINCE LAST ACTION
https://reviews.llvm.org/D87188/new/
https://reviews.llvm.org/D87188
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