Fix the remaining MUL8 and DIV8 to define AX instead of AL,AH.

These instructions technically define AL,AH, but a trick in X86ISelDAGToDAG
reads AX in order to avoid reading AH with a REX instruction.

Fix PR6489.

llvm-svn: 97742

1 files changed, 25 insertions, 0 deletions

diff --git a/llvm/test/CodeGen/X86/2010-03-04-Mul8Bug.ll b/llvm/test/CodeGen/X86/2010-03-04-Mul8Bug.ll
new file mode 100644
index 00000000000..48e75e95724
--- /dev/null
+++ b/llvm/test/CodeGen/X86/2010-03-04-Mul8Bug.ll
@@ -0,0 +1,25 @@
+; RUN: llc < %s
+; PR6489
+;
+; This test case produces a MUL8 instruction and then tries to read the result
+; from the AX register instead of AH/AL. That confuses live interval analysis.
+;
+target datalayout = "e-p:64:64:64-i1:8:8-i8:8:8-i16:16:16-i32:32:32-i64:64:64-f32:32:32-f64:64:64-v64:64:64-v128:128:128-a0:0:64-s0:64:64-f80:128:128-n8:16:32:64"
+target triple = "x86_64-apple-darwin10.0.0"
+
+define void @func_56(i64 %p_57, i32*** %p_58) nounwind ssp {
+for.end:
+  %conv49 = trunc i32 undef to i8                 ; <i8> [#uses=1]
+  %div.i = udiv i8 %conv49, 5                     ; <i8> [#uses=1]
+  %conv51 = zext i8 %div.i to i32                 ; <i32> [#uses=1]
+  %call55 = call i32 @qux(i32 undef, i32 -2) nounwind ; <i32> [#uses=1]
+  %rem.i = urem i32 %call55, -1                   ; <i32> [#uses=1]
+  %cmp57 = icmp uge i32 %conv51, %rem.i           ; <i1> [#uses=1]
+  %conv58 = zext i1 %cmp57 to i32                 ; <i32> [#uses=1]
+  %call85 = call i32 @func_35(i32*** undef, i32 undef, i32 %conv58, i32 1247, i32 0) nounwind ; <i32> [#uses=0]
+  ret void
+}
+
+declare i32 @func_35(i32***, i32, i32, i32, i32)
+
+declare i32 @qux(i32, i32)