[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.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@223220 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 25 insertions, 0 deletions

diff --git a/test/CodeGen/PowerPC/ia-neg-const.ll b/test/CodeGen/PowerPC/ia-neg-const.ll
new file mode 100644
index 00000000000..165fc1339d0
--- /dev/null
+++ b/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 }
+