CodeGenPrep: sink extends of illegal types into use block.

Summary:
This helps the instruction selector to lower an i64 * i64 -> i128
multiplication into a single instruction on targets which support it.

This is an update of D2973 which was reverted because of a bug reported
as PR19084.

Reviewers: t.p.northover, chapuni

Reviewed By: t.p.northover

CC: llvm-commits, alex, chapuni

Differential Revision: http://llvm-reviews.chandlerc.com/D3021

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@203797 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 64 insertions, 0 deletions

diff --git a/test/Transforms/CodeGenPrepare/X86/extend-sink-hoist.ll b/test/Transforms/CodeGenPrepare/X86/extend-sink-hoist.ll
new file mode 100644
index 0000000000..430b99299d
--- /dev/null
+++ b/test/Transforms/CodeGenPrepare/X86/extend-sink-hoist.ll
@@ -0,0 +1,64 @@
+; RUN: opt -codegenprepare -disable-cgp-branch-opts -S < %s | FileCheck %s
+target datalayout = "e-m:e-i64:64-f80:128-n8:16:32:64-S128"
+target triple = "x86_64-unknown-linux-gnu"
+
+; The first cast should be sunk into block2, in order that the
+; instruction selector can form an efficient
+; i64 * i64 -> i128 multiplication.
+define i128 @sink(i64* %mem1, i64* %mem2) {
+; CHECK-LABEL: block1:
+; CHECK-NEXT: load
+block1:
+  %l1 = load i64* %mem1
+  %s1 = sext i64 %l1 to i128
+  br label %block2
+
+; CHECK-LABEL: block2:
+; CHECK-NEXT: sext
+; CHECK-NEXT: load
+; CHECK-NEXT: sext
+block2:
+  %l2 = load i64* %mem2
+  %s2 = sext i64 %l2 to i128
+  %res = mul i128 %s1, %s2
+  ret i128 %res
+}
+
+; The first cast should be hoisted into block1, in order that the
+; instruction selector can form an extend-load.
+define i64 @hoist(i32* %mem1, i32* %mem2) {
+; CHECK-LABEL: block1:
+; CHECK-NEXT: load
+; CHECK-NEXT: sext
+block1:
+  %l1 = load i32* %mem1
+  br label %block2
+
+; CHECK-LABEL: block2:
+; CHECK-NEXT: load
+; CHECK-NEXT: sext
+block2:
+  %s1 = sext i32 %l1 to i64
+  %l2 = load i32* %mem2
+  %s2 = sext i32 %l2 to i64
+  %res = mul i64 %s1, %s2
+  ret i64 %res
+}
+
+; Make sure the cast sink logic and OptimizeExtUses don't end up in an infinite
+; loop.
+define i128 @use_ext_source() {
+block1:
+  %v1 = or i64 undef, undef
+  %v2 = zext i64 %v1 to i128
+  br i1 undef, label %block2, label %block3
+
+block2:
+  %v3 = add i64 %v1, 1
+  %v4 = zext i64 %v3 to i128
+  br label %block3
+
+block3:
+  %res = phi i128 [ %v2, %block1 ], [ %v4, %block2 ]
+  ret i128 %res
+}