[PATCH] D122825: [X86][FastISel] Fix with.overflow + select eflags clobber (PR54369)
Nikita Popov via Phabricator via llvm-commits
llvm-commits at lists.llvm.org
Fri Apr 8 03:35:57 PDT 2022
nikic updated this revision to Diff 421479.
nikic edited the summary of this revision.
nikic added a comment.
Rebase over new test.
CHANGES SINCE LAST ACTION
https://reviews.llvm.org/D122825/new/
https://reviews.llvm.org/D122825
Files:
llvm/lib/Target/X86/X86FastISel.cpp
llvm/test/CodeGen/X86/pr54369.ll
Index: llvm/test/CodeGen/X86/pr54369.ll
===================================================================
--- llvm/test/CodeGen/X86/pr54369.ll
+++ llvm/test/CodeGen/X86/pr54369.ll
@@ -1,16 +1,16 @@
; NOTE: Assertions have been autogenerated by utils/update_llc_test_checks.py
; RUN: llc -mtriple=x86_64-- -O0 < %s | FileCheck %s
-; FIXME: This is currently miscompiled due to an eflags clobber.
define i64 @adder(i64 %lhs, i64 %rhs) {
; CHECK-LABEL: adder:
; CHECK: # %bb.0:
; CHECK-NEXT: addq %rsi, %rdi
-; CHECK-NEXT: seto %al
+; CHECK-NEXT: seto %dl
; CHECK-NEXT: xorl %eax, %eax
; CHECK-NEXT: # kill: def $rax killed $eax
; CHECK-NEXT: movl $148, %ecx
-; CHECK-NEXT: cmovoq %rcx, %rax
+; CHECK-NEXT: testb $1, %dl
+; CHECK-NEXT: cmovneq %rcx, %rax
; CHECK-NEXT: retq
%res = call { i64, i1 } @llvm.sadd.with.overflow.i64(i64 %lhs, i64 %rhs)
%errorbit = extractvalue { i64, i1 } %res, 1
@@ -24,11 +24,12 @@
; CHECK-LABEL: adder_constexpr:
; CHECK: # %bb.0:
; CHECK-NEXT: addq %rsi, %rdi
-; CHECK-NEXT: seto %al
+; CHECK-NEXT: seto %dl
; CHECK-NEXT: movq a at GOTPCREL(%rip), %rax
; CHECK-NEXT: addq $5, %rax
; CHECK-NEXT: movl $148, %ecx
-; CHECK-NEXT: cmovoq %rcx, %rax
+; CHECK-NEXT: testb $1, %dl
+; CHECK-NEXT: cmovneq %rcx, %rax
; CHECK-NEXT: retq
%res = call { i64, i1 } @llvm.sadd.with.overflow.i64(i64 %lhs, i64 %rhs)
%errorbit = extractvalue { i64, i1 } %res, 1
Index: llvm/lib/Target/X86/X86FastISel.cpp
===================================================================
--- llvm/lib/Target/X86/X86FastISel.cpp
+++ llvm/lib/Target/X86/X86FastISel.cpp
@@ -281,6 +281,11 @@
if (I->isTerminator() && llvm::any_of(successors(I), HasPhis))
return false;
+ // Make sure there are no potentially eflags clobbering constant
+ // materializations in between.
+ if (llvm::any_of(I->operands(), [](Value *V) { return isa<Constant>(V); }))
+ return false;
+
CC = TmpCC;
return true;
}
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