[llvm-commits] [llvm] r89978 - in /llvm/trunk: lib/Analysis/MemoryDependenceAnalysis.cpp lib/Target/README.txt test/Transforms/GVN/rle-phi-translate.ll
Chris Lattner
sabre at nondot.org
Thu Nov 26 15:41:07 PST 2009
Author: lattner
Date: Thu Nov 26 17:41:07 2009
New Revision: 89978
URL: http://llvm.org/viewvc/llvm-project?rev=89978&view=rev
Log:
Teach memdep to phi translate bitcasts. This allows us to compile
the example in GCC PR16799 to:
LBB1_2: ## %bb1
movl %eax, %eax
subq %rax, %rdi
movq %rdi, (%rcx)
movl (%rdi), %eax
testl %eax, %eax
je LBB1_2
instead of:
LBB1_2: ## %bb1
movl (%rdi), %ecx
subq %rcx, %rdi
movq %rdi, (%rax)
cmpl $0, (%rdi)
je LBB1_2
Modified:
llvm/trunk/lib/Analysis/MemoryDependenceAnalysis.cpp
llvm/trunk/lib/Target/README.txt
llvm/trunk/test/Transforms/GVN/rle-phi-translate.ll
Modified: llvm/trunk/lib/Analysis/MemoryDependenceAnalysis.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Analysis/MemoryDependenceAnalysis.cpp?rev=89978&r1=89977&r2=89978&view=diff
==============================================================================
--- llvm/trunk/lib/Analysis/MemoryDependenceAnalysis.cpp (original)
+++ llvm/trunk/lib/Analysis/MemoryDependenceAnalysis.cpp Thu Nov 26 17:41:07 2009
@@ -690,10 +690,15 @@
if (isa<PHINode>(Inst))
return true;
- // TODO: BITCAST, GEP.
-
- // ...
+ // We can handle bitcast of a PHI, but the PHI needs to be in the same block
+ // as the bitcast.
+ if (BitCastInst *BC = dyn_cast<BitCastInst>(Inst))
+ if (PHINode *PN = dyn_cast<PHINode>(BC->getOperand(0)))
+ if (PN->getParent() == BC->getParent())
+ return true;
+ // TODO: GEP, ...
+
// cerr << "MEMDEP: Could not PHI translate: " << *Pointer;
// if (isa<BitCastInst>(PtrInst) || isa<GetElementPtrInst>(PtrInst))
// cerr << "OP:\t\t\t\t" << *PtrInst->getOperand(0);
@@ -708,6 +713,25 @@
if (PHINode *PN = dyn_cast<PHINode>(Inst))
return PN->getIncomingValueForBlock(Pred);
+ if (BitCastInst *BC = dyn_cast<BitCastInst>(Inst)) {
+ PHINode *BCPN = cast<PHINode>(BC->getOperand(0));
+ Value *PHIIn = BCPN->getIncomingValueForBlock(Pred);
+
+ // Constants are trivial to phi translate.
+ if (Constant *C = dyn_cast<Constant>(PHIIn))
+ return ConstantExpr::getBitCast(C, BC->getType());
+
+ // Otherwise we have to see if a bitcasted version of the incoming pointer
+ // is available. If so, we can use it, otherwise we have to fail.
+ for (Value::use_iterator UI = PHIIn->use_begin(), E = PHIIn->use_end();
+ UI != E; ++UI) {
+ if (BitCastInst *BCI = dyn_cast<BitCastInst>(*UI))
+ if (BCI->getType() == BC->getType())
+ return BCI;
+ }
+ return 0;
+ }
+
return 0;
}
Modified: llvm/trunk/lib/Target/README.txt
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Target/README.txt?rev=89978&r1=89977&r2=89978&view=diff
==============================================================================
--- llvm/trunk/lib/Target/README.txt (original)
+++ llvm/trunk/lib/Target/README.txt Thu Nov 26 17:41:07 2009
@@ -1284,8 +1284,6 @@
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=34677 (licm does this, LPRE crit edge)
llvm-gcc t2.c -S -o - -O0 -emit-llvm | llvm-as | opt -mem2reg -simplifycfg -gvn | llvm-dis
-http://gcc.gnu.org/bugzilla/show_bug.cgi?id=16799 [BITCAST PHI TRANS]
-
//===---------------------------------------------------------------------===//
Type based alias analysis:
Modified: llvm/trunk/test/Transforms/GVN/rle-phi-translate.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/Transforms/GVN/rle-phi-translate.ll?rev=89978&r1=89977&r2=89978&view=diff
==============================================================================
--- llvm/trunk/test/Transforms/GVN/rle-phi-translate.ll (original)
+++ llvm/trunk/test/Transforms/GVN/rle-phi-translate.ll Thu Nov 26 17:41:07 2009
@@ -4,6 +4,7 @@
target triple = "i386-apple-darwin7"
define i32 @test1(i32* %b, i32* %c) nounwind {
+; CHECK: @test1
entry:
%g = alloca i32
%t1 = icmp eq i32* %b, null
@@ -34,3 +35,28 @@
ret i32 %ret
}
+define i8 @test2(i1 %cond, i32* %b, i32* %c) nounwind {
+; CHECK: @test2
+entry:
+ br i1 %cond, label %bb, label %bb1
+
+bb:
+ %b1 = bitcast i32* %b to i8*
+ store i8 4, i8* %b1
+ br label %bb2
+
+bb1:
+ %c1 = bitcast i32* %c to i8*
+ store i8 92, i8* %c1
+ br label %bb2
+
+bb2:
+ %d = phi i32* [ %c, %bb1 ], [ %b, %bb ]
+ %d1 = bitcast i32* %d to i8*
+ %dv = load i8* %d1
+; CHECK: %dv = phi i8
+; CHECK-NOT: load
+; CHECK: ret i8 %dv
+ ret i8 %dv
+}
+
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