[llvm-commits] [llvm] r91631 - in /llvm/trunk: lib/Transforms/Scalar/InstructionCombining.cpp test/Transforms/InstCombine/2004-11-27-SetCCForCastLargerAndConstant.ll test/Transforms/InstCombine/2006-10-19-SignedToUnsignedCastAndConst.ll
Eli Friedman
eli.friedman at gmail.com
Thu Dec 17 14:42:30 PST 2009
Author: efriedma
Date: Thu Dec 17 16:42:29 2009
New Revision: 91631
URL: http://llvm.org/viewvc/llvm-project?rev=91631&view=rev
Log:
Allow instcombine to combine "sext(a) >u const" to "a >u trunc(const)".
Removed:
llvm/trunk/test/Transforms/InstCombine/2006-10-19-SignedToUnsignedCastAndConst.ll
Modified:
llvm/trunk/lib/Transforms/Scalar/InstructionCombining.cpp
llvm/trunk/test/Transforms/InstCombine/2004-11-27-SetCCForCastLargerAndConstant.ll
Modified: llvm/trunk/lib/Transforms/Scalar/InstructionCombining.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Transforms/Scalar/InstructionCombining.cpp?rev=91631&r1=91630&r2=91631&view=diff
==============================================================================
--- llvm/trunk/lib/Transforms/Scalar/InstructionCombining.cpp (original)
+++ llvm/trunk/lib/Transforms/Scalar/InstructionCombining.cpp Thu Dec 17 16:42:29 2009
@@ -7299,19 +7299,17 @@
// If the re-extended constant didn't change...
if (Res2 == CI) {
- // Make sure that sign of the Cmp and the sign of the Cast are the same.
- // For example, we might have:
- // %A = sext i16 %X to i32
- // %B = icmp ugt i32 %A, 1330
- // It is incorrect to transform this into
- // %B = icmp ugt i16 %X, 1330
- // because %A may have negative value.
- //
- // However, we allow this when the compare is EQ/NE, because they are
- // signless.
- if (isSignedExt == isSignedCmp || ICI.isEquality())
+ // Deal with equality cases early.
+ if (ICI.isEquality())
return new ICmpInst(ICI.getPredicate(), LHSCIOp, Res1);
- return 0;
+
+ // A signed comparison of sign extended values simplifies into a
+ // signed comparison.
+ if (isSignedExt && isSignedCmp)
+ return new ICmpInst(ICI.getPredicate(), LHSCIOp, Res1);
+
+ // The other three cases all fold into an unsigned comparison.
+ return new ICmpInst(ICI.getUnsignedPredicate(), LHSCIOp, Res1);
}
// The re-extended constant changed so the constant cannot be represented
Modified: llvm/trunk/test/Transforms/InstCombine/2004-11-27-SetCCForCastLargerAndConstant.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/Transforms/InstCombine/2004-11-27-SetCCForCastLargerAndConstant.ll?rev=91631&r1=91630&r2=91631&view=diff
==============================================================================
--- llvm/trunk/test/Transforms/InstCombine/2004-11-27-SetCCForCastLargerAndConstant.ll (original)
+++ llvm/trunk/test/Transforms/InstCombine/2004-11-27-SetCCForCastLargerAndConstant.ll Thu Dec 17 16:42:29 2009
@@ -33,6 +33,14 @@
; CHECK: ret i1 false
}
+define i1 @lt_signed_to_small_unsigned(i8 %SB) {
+ %Y = sext i8 %SB to i32
+ %C = icmp ult i32 %Y, 17
+ ret i1 %C
+; CHECK: %C = icmp ult i8 %SB, 17
+; CHECK: ret i1 %C
+}
+
define i1 @lt_signed_to_small_signed(i8 %SB) {
%Y = sext i8 %SB to i32 ; <i32> [#uses=1]
%C = icmp slt i32 %Y, 17 ; <i1> [#uses=1]
@@ -77,6 +85,14 @@
; CHECK: ret i1 %C
}
+define i1 @lt_unsigned_to_small_signed(i8 %SB) {
+ %Y = zext i8 %SB to i32
+ %C = icmp slt i32 %Y, 17
+ ret i1 %C
+; CHECK: %C = icmp ult i8 %SB, 17
+; CHECK: ret i1 %C
+}
+
define i1 @lt_unsigned_to_small_negative(i8 %SB) {
%Y = zext i8 %SB to i32 ; <i32> [#uses=1]
%C = icmp slt i32 %Y, -17 ; <i1> [#uses=1]
@@ -106,6 +122,14 @@
; CHECK: ret i1 true
}
+define i1 @gt_signed_to_small_unsigned(i8 %SB) {
+ %Y = sext i8 %SB to i32
+ %C = icmp ugt i32 %Y, 17
+ ret i1 %C
+; CHECK: %C = icmp ugt i8 %SB, 17
+; CHECK: ret i1 %C
+}
+
define i1 @gt_signed_to_small_signed(i8 %SB) {
%Y = sext i8 %SB to i32 ; <i32> [#uses=1]
%C = icmp sgt i32 %Y, 17 ; <i1> [#uses=1]
@@ -151,6 +175,14 @@
; CHECK: ret i1 %C
}
+define i1 @gt_unsigned_to_small_signed(i8 %SB) {
+ %Y = zext i8 %SB to i32
+ %C = icmp sgt i32 %Y, 17
+ ret i1 %C
+; CHECK: %C = icmp ugt i8 %SB, 17
+; CHECK: ret i1 %C
+}
+
define i1 @gt_unsigned_to_small_negative(i8 %SB) {
%Y = zext i8 %SB to i32 ; <i32> [#uses=1]
%C = icmp sgt i32 %Y, -17 ; <i1> [#uses=1]
Removed: llvm/trunk/test/Transforms/InstCombine/2006-10-19-SignedToUnsignedCastAndConst.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/Transforms/InstCombine/2006-10-19-SignedToUnsignedCastAndConst.ll?rev=91630&view=auto
==============================================================================
--- llvm/trunk/test/Transforms/InstCombine/2006-10-19-SignedToUnsignedCastAndConst.ll (original)
+++ llvm/trunk/test/Transforms/InstCombine/2006-10-19-SignedToUnsignedCastAndConst.ll (removed)
@@ -1,12 +0,0 @@
-; This test case is reduced from llvmAsmParser.cpp
-; The optimizer should not remove the cast here.
-; RUN: opt < %s -instcombine -S | \
-; RUN: grep sext.*i32
-
-
-define i1 @test(i16 %X) {
- %A = sext i16 %X to i32 ; <i32> [#uses=1]
- %B = icmp ugt i32 %A, 1330 ; <i1> [#uses=1]
- ret i1 %B
-}
-
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