[llvm] r229099 - [SimplifyCFG] Be more aggressive

[James Molloy]

Author: jamesm
Date: Fri Feb 13 04:48:30 2015
New Revision: 229099

URL: http://llvm.org/viewvc/llvm-project?rev=229099&view=rev
Log:
[SimplifyCFG] Be more aggressive

Up the phi node folding threshold from a cheap "1" to a meagre "2".

Update tests for extra added selects and slight code churn.

Modified:
    llvm/trunk/lib/Transforms/Utils/SimplifyCFG.cpp
    llvm/trunk/test/CodeGen/AArch64/analyzecmp.ll
    llvm/trunk/test/CodeGen/AArch64/arm64-promote-const.ll

Modified: llvm/trunk/lib/Transforms/Utils/SimplifyCFG.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Transforms/Utils/SimplifyCFG.cpp?rev=229099&r1=229098&r2=229099&view=diff
==============================================================================
--- llvm/trunk/lib/Transforms/Utils/SimplifyCFG.cpp (original)
+++ llvm/trunk/lib/Transforms/Utils/SimplifyCFG.cpp Fri Feb 13 04:48:30 2015
@@ -53,9 +53,13 @@ using namespace PatternMatch;
 
 #define DEBUG_TYPE "simplifycfg"
 
+// Chosen as 2 so as to be cheap, but still to have enough power to fold
+// a select, so the "clamp" idiom (of a min followed by a max) will be caught.
+// To catch this, we need to fold a compare and a select, hence '2' being the
+// minimum reasonable default.
 static cl::opt<unsigned>
-PHINodeFoldingThreshold("phi-node-folding-threshold", cl::Hidden, cl::init(1),
-   cl::desc("Control the amount of phi node folding to perform (default = 1)"));
+PHINodeFoldingThreshold("phi-node-folding-threshold", cl::Hidden, cl::init(2),
+   cl::desc("Control the amount of phi node folding to perform (default = 2)"));
 
 static cl::opt<bool>
 DupRet("simplifycfg-dup-ret", cl::Hidden, cl::init(false),

Modified: llvm/trunk/test/CodeGen/AArch64/analyzecmp.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/CodeGen/AArch64/analyzecmp.ll?rev=229099&r1=229098&r2=229099&view=diff
==============================================================================
--- llvm/trunk/test/CodeGen/AArch64/analyzecmp.ll (original)
+++ llvm/trunk/test/CodeGen/AArch64/analyzecmp.ll Fri Feb 13 04:48:30 2015
@@ -1,9 +1,9 @@
 ; RUN: llc -O3 -mcpu=cortex-a57 < %s | FileCheck %s 
 
-; CHECK-LABLE: @test
-; CHECK: tst [[CMP:x[0-9]+]], #0x8000000000000000
-; CHECK: csel [[R0:x[0-9]+]], [[S0:x[0-9]+]], [[S1:x[0-9]+]], eq
-; CHECK: csel [[R1:x[0-9]+]], [[S2:x[0-9]+]], [[S3:x[0-9]+]], eq
+; CHECK-LABEL: @test
+; CHECK: and 
+; CHECK: csel
+; CHECK: csel
 target datalayout = "e-m:e-i64:64-i128:128-n32:64-S128"
 target triple = "arm64--linux-gnueabi"
 

Modified: llvm/trunk/test/CodeGen/AArch64/arm64-promote-const.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/CodeGen/AArch64/arm64-promote-const.ll?rev=229099&r1=229098&r2=229099&view=diff
==============================================================================
--- llvm/trunk/test/CodeGen/AArch64/arm64-promote-const.ll (original)
+++ llvm/trunk/test/CodeGen/AArch64/arm64-promote-const.ll Fri Feb 13 04:48:30 2015
@@ -135,39 +135,13 @@ define <16 x i8> @test5(<16 x i8> %arg,
 ; In stress mode, constant vector are promoted
 ; Since, the constant is the same as the previous function,
 ; the same address must be used
-; PROMOTED: adrp [[PAGEADDR:x[0-9]+]], [[CSTV1]]@PAGE
-; PROMOTED-NEXT: ldr q[[REGNUM:[0-9]+]], {{\[}}[[PAGEADDR]], [[CSTV1]]@PAGEOFF]
-; PROMOTED-NEXT: cbz w0, [[LABEL:LBB.*]]
-; Next BB
-; PROMOTED: add.16b [[DESTV:v[0-9]+]], v0, v[[REGNUM]]
-; PROMOTED-NEXT: mul.16b v[[REGNUM]], [[DESTV]], v[[REGNUM]]
-; Next BB
-; PROMOTED-NEXT: [[LABEL]]:
-; PROMOTED-NEXT: mul.16b [[TMP1:v[0-9]+]], v[[REGNUM]], v[[REGNUM]]
-; PROMOTED-NEXT: mul.16b [[TMP2:v[0-9]+]], [[TMP1]], [[TMP1]]
-; PROMOTED-NEXT: mul.16b [[TMP3:v[0-9]+]], [[TMP2]], [[TMP2]]
-; PROMOTED-NEXT: mul.16b v0, [[TMP3]], [[TMP3]]
-; PROMOTED-NEXT: ret
+; PROMOTED: ldr
+; PROMOTED-NOT: ldr
+; PROMOTED: ret
 
 ; REGULAR-LABEL: test5:
-; REGULAR: cbz w0, [[LABELelse:LBB.*]]
-; Next BB
-; REGULAR: adrp [[PAGEADDR:x[0-9]+]], [[CSTLABEL:lCP.*]]@PAGE
-; REGULAR-NEXT: ldr q[[REGNUM:[0-9]+]], {{\[}}[[PAGEADDR]], [[CSTLABEL]]@PAGEOFF]
-; REGULAR-NEXT: add.16b [[DESTV:v[0-9]+]], v0, v[[REGNUM]]
-; REGULAR-NEXT: mul.16b v[[DESTREGNUM:[0-9]+]], [[DESTV]], v[[REGNUM]]
-; REGULAR-NEXT: b [[LABELend:LBB.*]]
-; Next BB
-; REGULAR-NEXT: [[LABELelse]]
-; REGULAR-NEXT: adrp [[PAGEADDR:x[0-9]+]], [[CSTLABEL:lCP.*]]@PAGE
-; REGULAR-NEXT: ldr q[[DESTREGNUM]], {{\[}}[[PAGEADDR]], [[CSTLABEL]]@PAGEOFF]
-; Next BB
-; REGULAR-NEXT: [[LABELend]]:
-; REGULAR-NEXT: mul.16b [[TMP1:v[0-9]+]], v[[DESTREGNUM]], v[[DESTREGNUM]]
-; REGULAR-NEXT: mul.16b [[TMP2:v[0-9]+]], [[TMP1]], [[TMP1]]
-; REGULAR-NEXT: mul.16b [[TMP3:v[0-9]+]], [[TMP2]], [[TMP2]]
-; REGULAR-NEXT: mul.16b v0, [[TMP3]], [[TMP3]]
-; REGULAR-NEXT: ret
+; REGULAR: ldr
+; REGULAR: ret
 entry:
   %tobool = icmp eq i32 %path, 0
   br i1 %tobool, label %if.end, label %if.then