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[PowerPC] Print all inline-asm consts as signed numbers

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Almost all immediates in PowerPC assembly (both 32-bit and 64-bit) are signed
numbers, and it is important that we print them as such. To make sure that
happens, we change PPCTargetLowering::LowerAsmOperandForConstraint so that it
does all intermediate checks on a signed-extended int64_t value, and then
creates the resulting target constant using MVT::i64. This will ensure that all
negative values are printed as negative values (mirroring what is done in other
backends to achieve the same sign-extension effect).

This came up in the context of inline assembly like this:
  "add%I2   %0,%0,%2", ..., "Ir"(-1ll)
where we used to print:
  addi   3,3,4294967295
and gcc would print:
  addi   3,3,-1
and gas accepts both forms, but our builtin assembler (correctly) does not. Now
we print -1 like gcc does.

While here, I replaced a bunch of custom integer checks with isInt<16> and
friends from MathExtras.h.

Thanks to Paul Hargrove for the bug report.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@223220 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Hal Finkel 2014-12-03 09:37:50 +00:00
parent 10cae8e352
commit cf988bca67
2 changed files with 43 additions and 13 deletions
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31
lib/Target/PowerPC/PPCISelLowering.cpp
View File

@ -8987,37 +8987,42 @@ void PPCTargetLowering::LowerAsmOperandForConstraint(SDValue Op,
case 'P': {
ConstantSDNode *CST = dyn_cast<ConstantSDNode>(Op);
if (!CST) return; // Must be an immediate to match.
unsigned Value = CST->getZExtValue();
int64_t Value = CST->getSExtValue();
EVT TCVT = MVT::i64; // All constants taken to be 64 bits so that negative
// numbers are printed as such.
switch (Letter) {
default: llvm_unreachable("Unknown constraint letter!");
case 'I': // "I" is a signed 16-bit constant.
if ((short)Value == (int)Value)
Result = DAG.getTargetConstant(Value, Op.getValueType());
if (isInt<16>(Value))
Result = DAG.getTargetConstant(Value, TCVT);
break;
case 'J': // "J" is a constant with only the high-order 16 bits nonzero.
if (isShiftedUInt<16, 16>(Value))
Result = DAG.getTargetConstant(Value, TCVT);
break;
case 'L': // "L" is a signed 16-bit constant shifted left 16 bits.
if ((short)Value == 0)
Result = DAG.getTargetConstant(Value, Op.getValueType());
if (isShiftedInt<16, 16>(Value))
Result = DAG.getTargetConstant(Value, TCVT);
break;
case 'K': // "K" is a constant with only the low-order 16 bits nonzero.
if ((Value >> 16) == 0)
Result = DAG.getTargetConstant(Value, Op.getValueType());
if (isUInt<16>(Value))
Result = DAG.getTargetConstant(Value, TCVT);
break;
case 'M': // "M" is a constant that is greater than 31.
if (Value > 31)
Result = DAG.getTargetConstant(Value, Op.getValueType());
Result = DAG.getTargetConstant(Value, TCVT);
break;
case 'N': // "N" is a positive constant that is an exact power of two.
if ((int)Value > 0 && isPowerOf2_32(Value))
Result = DAG.getTargetConstant(Value, Op.getValueType());
if (Value > 0 && isPowerOf2_64(Value))
Result = DAG.getTargetConstant(Value, TCVT);
break;
case 'O': // "O" is the constant zero.
if (Value == 0)
Result = DAG.getTargetConstant(Value, Op.getValueType());
Result = DAG.getTargetConstant(Value, TCVT);
break;
case 'P': // "P" is a constant whose negation is a signed 16-bit constant.
if ((short)-Value == (int)-Value)
Result = DAG.getTargetConstant(Value, Op.getValueType());
if (isInt<16>(-Value))
Result = DAG.getTargetConstant(Value, TCVT);
break;
}
break;

25
test/CodeGen/PowerPC/ia-neg-const.ll Normal file
View File

@ -0,0 +1,25 @@
; RUN: llc -mcpu=pwr7 < %s | FileCheck %s
target datalayout = "E-m:e-i64:64-n32:64"
target triple = "powerpc64-unknown-linux-gnu"
@.str = private unnamed_addr constant [5 x i8] c"%ld\0A\00", align 1
; Function Attrs: nounwind
define i64 @main() #0 {
entry:
%x = alloca i64, align 8
store i64 0, i64* %x, align 8
%0 = call i64 asm sideeffect "ld $0,$1\0A\09add${2:I} $0,$0,$2", "=&r,*m,Ir"(i64* %x, i64 -1) #0
ret i64 %0
}
; CHECK: ld
; CHECK-NOT: addi 3,3,4294967295
; CHECK: addi 3,3,-1
; CHECK: blr
; Function Attrs: nounwind
declare signext i32 @printf(i8* nocapture readonly, ...) #0
attributes #0 = { nounwind }