Teach instcombine 4 new xforms:

  (add (sext x), cst) --> (sext (add x, cst'))
  (add (sext x), (sext y)) --> (sext (add int x, y))
  (add double (sitofp x), fpcst) --> (sitofp (add int x, intcst))
  (add double (sitofp x), (sitofp y)) --> (sitofp (add int x, y))

This generally reduces conversions.  For example MiBench/telecomm-gsm
gets these simplifications:

HACK2: 	%tmp67.i142.i.i = sext i16 %tmp6.i141.i.i to i32		; <i32> [#uses=1]
	%tmp23.i139.i.i = sext i16 %tmp2.i138.i.i to i32		; <i32> [#uses=1]
	%tmp8.i143.i.i = add i32 %tmp67.i142.i.i, %tmp23.i139.i.i		; <i32> [#uses=3]
HACK2: 	%tmp67.i121.i.i = sext i16 %tmp6.i120.i.i to i32		; <i32> [#uses=1]
	%tmp23.i118.i.i = sext i16 %tmp2.i117.i.i to i32		; <i32> [#uses=1]
	%tmp8.i122.i.i = add i32 %tmp67.i121.i.i, %tmp23.i118.i.i		; <i32> [#uses=3]
HACK2: 	%tmp67.i.i190.i = sext i16 %tmp6.i.i189.i to i32		; <i32> [#uses=1]
	%tmp23.i.i187.i = sext i16 %tmp2.i.i186.i to i32		; <i32> [#uses=1]
	%tmp8.i.i191.i = add i32 %tmp67.i.i190.i, %tmp23.i.i187.i		; <i32> [#uses=3]
HACK2: 	%tmp67.i173.i.i.i = sext i16 %tmp6.i172.i.i.i to i32		; <i32> [#uses=1]
	%tmp23.i170.i.i.i = sext i16 %tmp2.i169.i.i.i to i32		; <i32> [#uses=1]
	%tmp8.i174.i.i.i = add i32 %tmp67.i173.i.i.i, %tmp23.i170.i.i.i		; <i32> [#uses=3]
HACK2: 	%tmp67.i152.i.i.i = sext i16 %tmp6.i151.i.i.i to i32		; <i32> [#uses=1]
	%tmp23.i149.i.i.i = sext i16 %tmp2.i148.i.i.i to i32		; <i32> [#uses=1]
	%tmp8.i153.i.i.i = add i32 %tmp67.i152.i.i.i, %tmp23.i149.i.i.i		; <i32> [#uses=3]
HACK2: 	%tmp67.i.i.i.i = sext i16 %tmp6.i.i.i.i to i32		; <i32> [#uses=1]
	%tmp23.i.i5.i.i = sext i16 %tmp2.i.i.i.i to i32		; <i32> [#uses=1]
	%tmp8.i.i7.i.i = add i32 %tmp67.i.i.i.i, %tmp23.i.i5.i.i		; <i32> [#uses=3]


This also fixes a bug in ComputeNumSignBits handling select and
makes it more aggressive with and/or.



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@51302 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 14 insertions, 0 deletions

diff --git a/test/Transforms/InstCombine/add-shrink.ll b/test/Transforms/InstCombine/add-shrink.ll
new file mode 100644
index 0000000..6dc02f3
--- /dev/null
+++ b/test/Transforms/InstCombine/add-shrink.ll
@@ -0,0 +1,14 @@
+; RUN: llvm-as < %s | opt -instcombine | llvm-dis | grep {add i32}
+; RUN: llvm-as < %s | opt -instcombine | llvm-dis | grep sext | count 1
+
+; Should only have one sext and the add should be i32 instead of i64.
+
+define i64 @test1(i32 %A) {
+	%B = ashr i32 %A, 7		; <i32> [#uses=1]
+	%C = ashr i32 %A, 9		; <i32> [#uses=1]
+	%D = sext i32 %B to i64		; <i64> [#uses=1]
+	%E = sext i32 %C to i64		; <i64> [#uses=1]
+	%F = add i64 %D, %E		; <i64> [#uses=1]
+	ret i64 %F
+}
+