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Revert to extend i8/i16 return values on Darwin (PR26665) 

In r260133, LLVM was changed to no longer extend i8/i16 return values,
as it's not required by the ABI. However, code was found in the wild
that relies on the old behaviour on Darwin, so this commit reverts
back to that old behaviour for Darwin.

On other platforms, it's less likely that code would be depending on
the old behaviour, as GCC and MSVC haven't been extending such return
values.

llvm-svn: 261235
This commit is contained in:
Hans Wennborg 2016-02-18 18:17:05 +00:00
parent 3a16e2a26a
commit 23cdc643b9
5 changed files with 39 additions and 12 deletions
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7
llvm/lib/Target/X86/X86ISelLowering.cpp
View File

@ -2382,8 +2382,13 @@ EVT X86TargetLowering::getTypeForExtReturn(LLVMContext &Context, EVT VT,
ISD::NodeType ExtendKind) const {
MVT ReturnMVT = MVT::i32;
if (VT == MVT::i1 || VT == MVT::i8 || VT == MVT::i16) {
bool Darwin = Subtarget.getTargetTriple().isOSDarwin();
if (VT == MVT::i1 || (!Darwin && (VT == MVT::i8 || VT == MVT::i16))) {
// The ABI does not require i1, i8 or i16 to be extended.
//
// On Darwin, there is code in the wild relying on Clang's old behaviour of
// always extending i8/i16 return values, so keep doing that for now.
// (PR26665).
ReturnMVT = MVT::i8;
}

10
llvm/test/CodeGen/X86/3addr-16bit.ll
View File

@ -12,7 +12,7 @@ entry:
; 64BIT-LABEL: t1:
; 64BIT-NOT: movw %si, %ax
; 64BIT: leal 1(%rsi), %ebx
; 64BIT: leal 1(%rsi), %eax
%0 = icmp eq i16 %k, %c ; <i1> [#uses=1]
%1 = add i16 %k, 1 ; <i16> [#uses=3]
br i1 %0, label %bb, label %bb1
@ -34,8 +34,8 @@ entry:
; 64BIT-LABEL: t2:
; 64BIT-NOT: movw %si, %ax
; 64BIT: leal -1(%rsi), %ebx
; 64BIT: movzwl %bx
; 64BIT: leal -1(%rsi), %eax
; 64BIT: movzwl %ax
%0 = icmp eq i16 %k, %c ; <i1> [#uses=1]
%1 = add i16 %k, -1 ; <i16> [#uses=3]
br i1 %0, label %bb, label %bb1
@ -59,7 +59,7 @@ entry:
; 64BIT-LABEL: t3:
; 64BIT-NOT: movw %si, %ax
; 64BIT: leal 2(%rsi), %ebx
; 64BIT: leal 2(%rsi), %eax
%0 = add i16 %k, 2 ; <i16> [#uses=3]
%1 = icmp eq i16 %k, %c ; <i1> [#uses=1]
br i1 %1, label %bb, label %bb1
@ -82,7 +82,7 @@ entry:
; 64BIT-LABEL: t4:
; 64BIT-NOT: movw %si, %ax
; 64BIT: leal (%rsi,%rdi), %ebx
; 64BIT: leal (%rsi,%rdi), %eax
%0 = add i16 %k, %c ; <i16> [#uses=3]
%1 = icmp eq i16 %k, %c ; <i1> [#uses=1]
br i1 %1, label %bb, label %bb1

8
llvm/test/CodeGen/X86/divrem8_ext.ll
View File

@ -6,9 +6,9 @@ target triple = "x86_64-apple-macosx10.10.0"
define zeroext i8 @test_udivrem_zext_ah(i8 %x, i8 %y) {
; CHECK-LABEL: test_udivrem_zext_ah
; CHECK: divb
; CHECK: movzbl %ah, %e[[REG_REM:[a-z]]]x
; CHECK: movzbl %ah, [[REG_REM:%[a-z0-9]+]]
; CHECK: movb %al, ([[REG_ZPTR:%[a-z0-9]+]])
; CHECK: movb %[[REG_REM]]l, %al
; CHECK: movl [[REG_REM]], %eax
; CHECK: ret
%div = udiv i8 %x, %y
store i8 %div, i8* @z
@ -51,9 +51,9 @@ define signext i8 @test_sdivrem_sext_ah(i8 %x, i8 %y) {
; CHECK-LABEL: test_sdivrem_sext_ah
; CHECK: cbtw
; CHECK: idivb
; CHECK: movsbl %ah, %e[[REG_REM:[a-z]]]x
; CHECK: movsbl %ah, [[REG_REM:%[a-z0-9]+]]
; CHECK: movb %al, ([[REG_ZPTR]])
; CHECK: movb %[[REG_REM]]l, %al
; CHECK: movl [[REG_REM]], %eax
; CHECK: ret
%div = sdiv i8 %x, %y
store i8 %div, i8* @z

22
llvm/test/CodeGen/X86/return-ext.ll
View File

@ -1,5 +1,6 @@
; RUN: llc < %s -mtriple=i686-unknown-linux-gnu | FileCheck %s
; RUN: llc < %s -mtriple=x86_64-unknown-linux-gnu | FileCheck %s
; RUN: llc < %s -mtriple=x86_64-apple-darwin | FileCheck -check-prefix=DARWIN %s
@x = common global i32 0, align 4
@ -29,6 +30,13 @@ entry:
; CHECK: cmp
; CHECK-NEXT: sete
; CHECK-NEXT: ret
; Except on Darwin, for legacy reasons.
; DARWIN-LABEL: unsigned_i8:
; DARWIN: cmp
; DARWIN-NEXT: sete
; DARWIN-NEXT: movzbl
; DARWIN-NEXT: ret
}
define signext i8 @signed_i8() {
@ -43,6 +51,13 @@ entry:
; CHECK: cmp
; CHECK-NEXT: sete
; CHECK-NEXT: ret
; Except on Darwin, for legacy reasons.
; DARWIN-LABEL: signed_i8:
; DARWIN: cmp
; DARWIN-NEXT: sete
; DARWIN-NEXT: movzbl
; DARWIN-NEXT: ret
}
@a = common global i16 0
@ -59,6 +74,13 @@ entry:
; CHECK: movw
; CHECK-NEXT: addw
; CHECK-NEXT: ret
; Except on Darwin, for legay reasons.
; DARWIN-LABEL: unsigned_i16:
; DARWIN: movw
; DARWIN-NEXT: addw
; DARWIN-NEXT: movzwl
; DARWIN-NEXT: ret
}

4
llvm/test/CodeGen/X86/select.ll
View File

@ -66,10 +66,10 @@ entry:
%2 = load i8, i8* %1, align 1 ; <i8> [#uses=1]
ret i8 %2
; CHECK-LABEL: test4:
; CHECK: movb ({{.*}},4), %al
; CHECK: movsbl ({{.*}},4), %eax
; ATOM-LABEL: test4:
; ATOM: movb ({{.*}},4), %al
; ATOM: movsbl ({{.*}},4), %eax
}
define void @test5(i1 %c, <2 x i16> %a, <2 x i16> %b, <2 x i16>* %p) nounwind {