[PowerPC] [FastISel] i1 constants must be zero extended

When materializing constant i1 values, they must be zero extended. We represent
i1 values as [0, 1], not [0, -1], in i32 registers. As it turns out, this code
path was dead for i1 values prior to r216006 (which is why this did not manifest in
miscompiles until recently).

Fixes -O0 self-hosting on PPC64/Linux.

llvm-svn: 224842

1 files changed, 27 insertions, 0 deletions

diff --git a/llvm/test/CodeGen/PowerPC/fast-isel-const.ll b/llvm/test/CodeGen/PowerPC/fast-isel-const.ll
new file mode 100644
index 00000000000..1057d0a0ce2
--- /dev/null
+++ b/llvm/test/CodeGen/PowerPC/fast-isel-const.ll
@@ -0,0 +1,27 @@
+; RUN: llc < %s -O0 -verify-machineinstrs -fast-isel-abort -mtriple=powerpc64-unknown-linux-gnu -mcpu=pwr7 -mattr=-vsx | FileCheck %s --check-prefix=ELF64
+
+define zeroext i1 @testi1(i8 %in) nounwind uwtable ssp {
+entry:
+  %c = icmp eq i8 %in, 5
+  br i1 %c, label %true, label %false
+
+; ELF64-LABEL: @testi1
+
+true:
+  br label %end
+
+; ELF64-NOT: li {{[0-9]+}}, -1
+; ELF64: li {{[0-9]+}}, 1
+
+false:
+  br label %end
+
+; ELF64: li {{[0-9]+}}, 0
+
+end:
+  %r = phi i1 [ 0, %false], [ 1, %true ]
+  ret i1 %r
+
+; ELF64: blr
+}
+