[llvm-commits] [llvm] r123105 - in /llvm/trunk: lib/Analysis/ScalarEvolution.cpp test/Analysis/ScalarEvolution/nsw.ll

[Chris Lattner]

Author: lattner
Date: Sat Jan  8 20:28:48 2011
New Revision: 123105

URL: http://llvm.org/viewvc/llvm-project?rev=123105&view=rev
Log:
teach SCEV analysis of PHI nodes that PHI recurences formed
with GEP instructions are always NUW, because PHIs cannot wrap
the end of the address space.

Modified:
    llvm/trunk/lib/Analysis/ScalarEvolution.cpp
    llvm/trunk/test/Analysis/ScalarEvolution/nsw.ll

Modified: llvm/trunk/lib/Analysis/ScalarEvolution.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Analysis/ScalarEvolution.cpp?rev=123105&r1=123104&r2=123105&view=diff
==============================================================================
--- llvm/trunk/lib/Analysis/ScalarEvolution.cpp (original)
+++ llvm/trunk/lib/Analysis/ScalarEvolution.cpp Sat Jan  8 20:28:48 2011
@@ -2719,6 +2719,11 @@
                   HasNUW = true;
                 if (OBO->hasNoSignedWrap())
                   HasNSW = true;
+              } else if (isa<GEPOperator>(BEValueV)) {
+                // If the increment is a GEP, then we know it won't perform an
+                // unsigned overflow, because the address space cannot be
+                // wrapped around.
+                HasNUW = true;
               }
 
               const SCEV *StartVal = getSCEV(StartValueV);

Modified: llvm/trunk/test/Analysis/ScalarEvolution/nsw.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/Analysis/ScalarEvolution/nsw.ll?rev=123105&r1=123104&r2=123105&view=diff
==============================================================================
--- llvm/trunk/test/Analysis/ScalarEvolution/nsw.ll (original)
+++ llvm/trunk/test/Analysis/ScalarEvolution/nsw.ll Sat Jan  8 20:28:48 2011
@@ -1,10 +1,11 @@
-; RUN: opt < %s -analyze -scalar-evolution | grep { -->  {.*,+,.*}.*<%bb>} | count 8
+; RUN: opt < %s -analyze -scalar-evolution | FileCheck %s
 
 ; The addrecs in this loop are analyzable only by using nsw information.
 
 target datalayout = "e-p:64:64:64-i1:8:8-i8:8:8-i16:16:16-i32:32:32-i64:64:64"
 
-define void @foo(double* %p) nounwind {
+; CHECK: Classifying expressions for: @test1
+define void @test1(double* %p) nounwind {
 entry:
 	%tmp = load double* %p, align 8		; <double> [#uses=1]
 	%tmp1 = fcmp ogt double %tmp, 2.000000e+00		; <i1> [#uses=1]
@@ -15,19 +16,29 @@
 
 bb:		; preds = %bb1, %bb.nph
 	%i.01 = phi i32 [ %tmp8, %bb1 ], [ 0, %bb.nph ]		; <i32> [#uses=3]
+; CHECK: %i.01
+; CHECK-NEXT: -->  {0,+,1}<nuw><nsw><%bb>
 	%tmp2 = sext i32 %i.01 to i64		; <i64> [#uses=1]
 	%tmp3 = getelementptr double* %p, i64 %tmp2		; <double*> [#uses=1]
 	%tmp4 = load double* %tmp3, align 8		; <double> [#uses=1]
 	%tmp5 = fmul double %tmp4, 9.200000e+00		; <double> [#uses=1]
 	%tmp6 = sext i32 %i.01 to i64		; <i64> [#uses=1]
 	%tmp7 = getelementptr double* %p, i64 %tmp6		; <double*> [#uses=1]
+; CHECK: %tmp7
+; CHECK-NEXT:   -->  {%p,+,8}<%bb>
 	store double %tmp5, double* %tmp7, align 8
 	%tmp8 = add nsw i32 %i.01, 1		; <i32> [#uses=2]
+; CHECK: %tmp8
+; CHECK-NEXT: -->  {1,+,1}<nuw><nsw><%bb>
 	br label %bb1
 
 bb1:		; preds = %bb
 	%phitmp = sext i32 %tmp8 to i64		; <i64> [#uses=1]
+; CHECK: %phitmp
+; CHECK-NEXT: -->  {1,+,1}<%bb>
 	%tmp9 = getelementptr double* %p, i64 %phitmp		; <double*> [#uses=1]
+; CHECK: %tmp9
+; CHECK-NEXT:  -->  {(8 + %p),+,8}<%bb>
 	%tmp10 = load double* %tmp9, align 8		; <double> [#uses=1]
 	%tmp11 = fcmp ogt double %tmp10, 2.000000e+00		; <i1> [#uses=1]
 	br i1 %tmp11, label %bb, label %bb1.return_crit_edge
@@ -38,3 +49,30 @@
 return:		; preds = %bb1.return_crit_edge, %entry
 	ret void
 }
+
+; CHECK: Classifying expressions for: @test2
+define void @test2(i32* %begin, i32* %end) ssp {
+entry:
+  %cmp1.i.i = icmp eq i32* %begin, %end
+  br i1 %cmp1.i.i, label %_ZSt4fillIPiiEvT_S1_RKT0_.exit, label %for.body.lr.ph.i.i
+
+for.body.lr.ph.i.i:                               ; preds = %entry
+  br label %for.body.i.i
+
+for.body.i.i:                                     ; preds = %for.body.i.i, %for.body.lr.ph.i.i
+  %__first.addr.02.i.i = phi i32* [ %begin, %for.body.lr.ph.i.i ], [ %ptrincdec.i.i, %for.body.i.i ]
+; CHECK: %__first.addr.02.i.i
+; CHECK-NEXT: -->  {%begin,+,4}<nuw><%for.body.i.i>	
+  store i32 0, i32* %__first.addr.02.i.i, align 4
+  %ptrincdec.i.i = getelementptr inbounds i32* %__first.addr.02.i.i, i64 1
+; CHECK: %ptrincdec.i.i
+; CHECK-NEXT: -->  {(4 + %begin),+,4}<nuw><%for.body.i.i>
+  %cmp.i.i = icmp eq i32* %ptrincdec.i.i, %end
+  br i1 %cmp.i.i, label %for.cond.for.end_crit_edge.i.i, label %for.body.i.i
+
+for.cond.for.end_crit_edge.i.i:                   ; preds = %for.body.i.i
+  br label %_ZSt4fillIPiiEvT_S1_RKT0_.exit
+
+_ZSt4fillIPiiEvT_S1_RKT0_.exit:                   ; preds = %entry, %for.cond.for.end_crit_edge.i.i
+  ret void
+}