6502/llvm-6502
1
0
Fork 0
mirror of https://github.com/c64scene-ar/llvm-6502.git synced 2024-12-14 11:32:34 +00:00
Code Issues Projects Releases Wiki Activity

don't eliminate load from volatile value on paths where the load is dead.

Browse Source 
This fixes the second half of PR2262


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@50430 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Chris Lattner 2008-04-29 17:28:22 +00:00
parent 68608e4dd0
commit 40700fe683
2 changed files with 34 additions and 0 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

9
lib/Transforms/Scalar/InstructionCombining.cpp
View File

@ -9396,6 +9396,15 @@ Instruction *InstCombiner::FoldPHIArgOpIntoPHI(PHINode &PN) {
LI->getParent() != PN.getIncomingBlock(i) ||
!isSafeToSinkLoad(LI))
return 0;
// If the PHI is volatile and its block has multiple successors, sinking
// it would remove a load of the volatile value from the path through the
// other successor.
if (isVolatile &&
LI->getParent()->getTerminator()->getNumSuccessors() != 1)
return 0;
} else if (I->getOperand(1) != ConstantOp) {
return 0;
}

25
test/Transforms/InstCombine/2008-04-29-VolatileLoadDontMerge.ll Normal file
View File

@ -0,0 +1,25 @@
; RUN: llvm-as < %s | opt -instcombine | llvm-dis | grep {volatile load} | count 2
target datalayout = "e-p:32:32:32-i1:8:8-i8:8:8-i16:16:16-i32:32:32-i64:32:64-f32:32:32-f64:32:64-v64:64:64-v128:128:128-a0:0:64-f80:128:128"
target triple = "i386-apple-darwin8"
@g_1 = internal global i32 0 ; <i32*> [#uses=3]
define i32 @main() nounwind {
entry:
%tmp93 = icmp slt i32 0, 10 ; <i1> [#uses=0]
%tmp34 = volatile load i32* @g_1, align 4 ; <i32> [#uses=1]
br label %bb
bb: ; preds = %bb, %entry
%b.0.reg2mem.0 = phi i32 [ 0, %entry ], [ %tmp6, %bb ] ; <i32> [#uses=1]
%tmp3.reg2mem.0 = phi i32 [ %tmp34, %entry ], [ %tmp3, %bb ] ; <i32> [#uses=1]
%tmp4 = add i32 %tmp3.reg2mem.0, 5 ; <i32> [#uses=1]
volatile store i32 %tmp4, i32* @g_1, align 4
%tmp6 = add i32 %b.0.reg2mem.0, 1 ; <i32> [#uses=2]
%tmp9 = icmp slt i32 %tmp6, 10 ; <i1> [#uses=1]
%tmp3 = volatile load i32* @g_1, align 4 ; <i32> [#uses=1]
br i1 %tmp9, label %bb, label %bb11
bb11: ; preds = %bb
ret i32 0
}