it turns out that when ".with.overflow" intrinsics were added to the X86
backend that they were all implemented except umul. This one fell back
to the default implementation that did a hi/lo multiply and compared the
top. Fix this to check the overflow flag that the 'mul' instruction
sets, so we can avoid an explicit test. Now we compile:
void *func(long count) {
return new int[count];
}
into:
__Z4funcl: ## @_Z4funcl
movl $4, %ecx ## encoding: [0xb9,0x04,0x00,0x00,0x00]
movq %rdi, %rax ## encoding: [0x48,0x89,0xf8]
mulq %rcx ## encoding: [0x48,0xf7,0xe1]
seto %cl ## encoding: [0x0f,0x90,0xc1]
testb %cl, %cl ## encoding: [0x84,0xc9]
movq $-1, %rdi ## encoding: [0x48,0xc7,0xc7,0xff,0xff,0xff,0xff]
cmoveq %rax, %rdi ## encoding: [0x48,0x0f,0x44,0xf8]
jmp __Znam ## TAILCALL
instead of:
__Z4funcl: ## @_Z4funcl
movl $4, %ecx ## encoding: [0xb9,0x04,0x00,0x00,0x00]
movq %rdi, %rax ## encoding: [0x48,0x89,0xf8]
mulq %rcx ## encoding: [0x48,0xf7,0xe1]
testq %rdx, %rdx ## encoding: [0x48,0x85,0xd2]
movq $-1, %rdi ## encoding: [0x48,0xc7,0xc7,0xff,0xff,0xff,0xff]
cmoveq %rax, %rdi ## encoding: [0x48,0x0f,0x44,0xf8]
jmp __Znam ## TAILCALL
Other than the silly seto+test, this is using the o bit directly, so it's going in the right
direction.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@120935 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/test/CodeGen/X86/umul-with-overflow.ll b/test/CodeGen/X86/umul-with-overflow.ll
index d522bd8..c997661 100644
--- a/test/CodeGen/X86/umul-with-overflow.ll
+++ b/test/CodeGen/X86/umul-with-overflow.ll
@@ -1,8 +1,14 @@
-; RUN: llc < %s -march=x86 | grep "\\\\\\\<mul"
+; RUN: llc < %s -march=x86 | FileCheck %s
declare {i32, i1} @llvm.umul.with.overflow.i32(i32 %a, i32 %b)
define i1 @a(i32 %x) zeroext nounwind {
%res = call {i32, i1} @llvm.umul.with.overflow.i32(i32 %x, i32 3)
%obil = extractvalue {i32, i1} %res, 1
ret i1 %obil
+
+; CHECK: a:
+; CHECK: mull
+; CHECK: seto %al
+; CHECK: movzbl %al, %eax
+; CHECK: ret
}