[llvm-commits] [llvm] r151807 - in /llvm/trunk: lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp test/CodeGen/ARM/log2_not_readnone.ll test/CodeGen/X86/log2_not_readnone.ll

[James Molloy]

Author: jamesm
Date: Thu Mar  1 08:32:18 2012
New Revision: 151807

URL: http://llvm.org/viewvc/llvm-project?rev=151807&view=rev
Log:
Fix a codegen fault in which log2 or exp2 could be dead-code eliminated even though they could have sideeffects.

Only allow log2/exp2 to be converted to an intrinsic if they are declared "readnone".


Added:
    llvm/trunk/test/CodeGen/ARM/log2_not_readnone.ll   (with props)
    llvm/trunk/test/CodeGen/X86/log2_not_readnone.ll   (with props)
Modified:
    llvm/trunk/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp

Modified: llvm/trunk/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp?rev=151807&r1=151806&r2=151807&view=diff
==============================================================================
--- llvm/trunk/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp (original)
+++ llvm/trunk/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp Thu Mar  1 08:32:18 2012
@@ -5627,7 +5627,8 @@
                  (LibInfo->has(LibFunc::log2l) && Name == "log2l")) {
         if (I.getNumArgOperands() == 1 && // Basic sanity checks.
             I.getArgOperand(0)->getType()->isFloatingPointTy() &&
-            I.getType() == I.getArgOperand(0)->getType()) {
+            I.getType() == I.getArgOperand(0)->getType() &&
+            I.onlyReadsMemory()) {
           SDValue Tmp = getValue(I.getArgOperand(0));
           setValue(&I, DAG.getNode(ISD::FLOG2, getCurDebugLoc(),
                                    Tmp.getValueType(), Tmp));
@@ -5638,7 +5639,8 @@
                  (LibInfo->has(LibFunc::exp2l) && Name == "exp2l")) {
         if (I.getNumArgOperands() == 1 && // Basic sanity checks.
             I.getArgOperand(0)->getType()->isFloatingPointTy() &&
-            I.getType() == I.getArgOperand(0)->getType()) {
+            I.getType() == I.getArgOperand(0)->getType() &&
+            I.onlyReadsMemory()) {
           SDValue Tmp = getValue(I.getArgOperand(0));
           setValue(&I, DAG.getNode(ISD::FEXP2, getCurDebugLoc(),
                                    Tmp.getValueType(), Tmp));

Added: llvm/trunk/test/CodeGen/ARM/log2_not_readnone.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/CodeGen/ARM/log2_not_readnone.ll?rev=151807&view=auto
==============================================================================
--- llvm/trunk/test/CodeGen/ARM/log2_not_readnone.ll (added)
+++ llvm/trunk/test/CodeGen/ARM/log2_not_readnone.ll Thu Mar  1 08:32:18 2012
@@ -0,0 +1,15 @@
+; RUN: llc -march arm %s -o - | FileCheck %s
+
+; Log2 and exp2 are string-matched to intrinsics. If they are not declared
+; readnone, they can't be changed to intrinsics (because they can change errno).
+
+declare double @log2(double)
+declare double @exp2(double)
+
+define void @f() {
+       ; CHECK: bl log2
+       %1 = call double @log2(double 0.000000e+00)
+       ; CHECK: bl exp2
+       %2 = call double @exp2(double 0.000000e+00)
+       ret void
+}

Propchange: llvm/trunk/test/CodeGen/ARM/log2_not_readnone.ll
------------------------------------------------------------------------------
    svn:eol-style = native

Added: llvm/trunk/test/CodeGen/X86/log2_not_readnone.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/CodeGen/X86/log2_not_readnone.ll?rev=151807&view=auto
==============================================================================
--- llvm/trunk/test/CodeGen/X86/log2_not_readnone.ll (added)
+++ llvm/trunk/test/CodeGen/X86/log2_not_readnone.ll Thu Mar  1 08:32:18 2012
@@ -0,0 +1,15 @@
+; RUN: llc -march x86 %s -o - | FileCheck %s
+
+; Log2 and exp2 are string-matched to intrinsics. If they are not declared
+; readnone, they can't be changed to intrinsics (because they can change errno).
+
+declare double @log2(double)
+declare double @exp2(double)
+
+define void @f() {
+       ; CHECK: calll log2
+       %1 = call double @log2(double 0.000000e+00)
+       ; CHECK: calll exp2
+       %2 = call double @exp2(double 0.000000e+00)
+       ret void
+}

Propchange: llvm/trunk/test/CodeGen/X86/log2_not_readnone.ll
------------------------------------------------------------------------------
    svn:eol-style = native