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

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.

llvm-svn: 223220

diff --git a/llvm/lib/Target/PowerPC/PPCISelLowering.cpp b/llvm/lib/Target/PowerPC/PPCISelLowering.cpp
index d913f3b..10e4e60 100644 (file)
--- a/llvm/lib/Target/PowerPC/PPCISelLowering.cpp
+++ b/llvm/lib/Target/PowerPC/PPCISelLowering.cpp
@@ -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;

diff --git a/llvm/test/CodeGen/PowerPC/ia-neg-const.ll b/llvm/test/CodeGen/PowerPC/ia-neg-const.ll
new file mode 100644 (file)
index 0000000..165fc13
--- /dev/null
+++ b/llvm/test/CodeGen/PowerPC/ia-neg-const.ll
@@ -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 }
+