Generalize ExtendUsesToFormExtLoad to be usable for ANY_EXTEND,
in addition to ZERO_EXTEND and SIGN_EXTEND. Fix a bug in the
way it checked for live-out values, and simplify the way it
find users by using SDNode::use_iterator's (relatively) new
features. Also, make it slightly more permissive on targets
with free truncates.
In SelectionDAGBuild, avoid creating ANY_EXTEND nodes that are
larger than necessary. If the target's SwitchAmountTy has
enough bits, use it. This exposes the truncate to optimization
early, enabling more optimizations.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@68670 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/test/CodeGen/X86/switch-zextload.ll b/test/CodeGen/X86/switch-zextload.ll
new file mode 100644
index 0000000..f3c701f
--- /dev/null
+++ b/test/CodeGen/X86/switch-zextload.ll
@@ -0,0 +1,34 @@
+; RUN: llvm-as < %s | llc -march=x86 | grep mov | count 1
+
+; Do zextload, instead of a load and a separate zext.
+
+target datalayout = "e-p:32:32:32-i1:8:8-i8:8:8-i16:16:16-i32:32:32-i64:32:64-f32:32:32-f64:32:64-v64:64:64-v128:128:128-a0:0:64-f80:128:128"
+target triple = "i386-apple-darwin9.6"
+ %struct.move_s = type { i32, i32, i32, i32, i32, i32 }
+ %struct.node_t = type { i8, i8, i8, i8, i32, i32, %struct.node_t**, %struct.node_t*, %struct.move_s }
+
+define fastcc void @set_proof_and_disproof_numbers(%struct.node_t* nocapture %node) nounwind {
+entry:
+ %0 = load i8* null, align 1 ; <i8> [#uses=1]
+ switch i8 %0, label %return [
+ i8 2, label %bb31
+ i8 0, label %bb80
+ i8 1, label %bb82
+ i8 3, label %bb84
+ ]
+
+bb31: ; preds = %entry
+ unreachable
+
+bb80: ; preds = %entry
+ ret void
+
+bb82: ; preds = %entry
+ ret void
+
+bb84: ; preds = %entry
+ ret void
+
+return: ; preds = %entry
+ ret void
+}