llvm-project/llvm/test/Analysis/ScalarEvolution/max-trip-count.ll

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; RUN: opt < %s -analyze -scalar-evolution | FileCheck %s
; ScalarEvolution should be able to understand the loop and eliminate the casts.
; CHECK: {%d,+,4}
define void @foo(i32* nocapture %d, i32 %n) nounwind {
entry:
%0 = icmp sgt i32 %n, 0 ; <i1> [#uses=1]
br i1 %0, label %bb.nph, label %return
bb.nph: ; preds = %entry
br label %bb
bb: ; preds = %bb1, %bb.nph
%i.02 = phi i32 [ %5, %bb1 ], [ 0, %bb.nph ] ; <i32> [#uses=2]
%p.01 = phi i8 [ %4, %bb1 ], [ -1, %bb.nph ] ; <i8> [#uses=2]
%1 = sext i8 %p.01 to i32 ; <i32> [#uses=1]
%2 = sext i32 %i.02 to i64 ; <i64> [#uses=1]
[opaque pointer type] Add textual IR support for explicit type parameter to getelementptr instruction One of several parallel first steps to remove the target type of pointers, replacing them with a single opaque pointer type. This adds an explicit type parameter to the gep instruction so that when the first parameter becomes an opaque pointer type, the type to gep through is still available to the instructions. * This doesn't modify gep operators, only instructions (operators will be handled separately) * Textual IR changes only. Bitcode (including upgrade) and changing the in-memory representation will be in separate changes. * geps of vectors are transformed as: getelementptr <4 x float*> %x, ... ->getelementptr float, <4 x float*> %x, ... Then, once the opaque pointer type is introduced, this will ultimately look like: getelementptr float, <4 x ptr> %x with the unambiguous interpretation that it is a vector of pointers to float. * address spaces remain on the pointer, not the type: getelementptr float addrspace(1)* %x ->getelementptr float, float addrspace(1)* %x Then, eventually: getelementptr float, ptr addrspace(1) %x Importantly, the massive amount of test case churn has been automated by same crappy python code. I had to manually update a few test cases that wouldn't fit the script's model (r228970,r229196,r229197,r229198). The python script just massages stdin and writes the result to stdout, I then wrapped that in a shell script to handle replacing files, then using the usual find+xargs to migrate all the files. update.py: import fileinput import sys import re ibrep = re.compile(r"(^.*?[^%\w]getelementptr inbounds )(((?:<\d* x )?)(.*?)(| addrspace\(\d\)) *\*(|>)(?:$| *(?:%|@|null|undef|blockaddress|getelementptr|addrspacecast|bitcast|inttoptr|\[\[[a-zA-Z]|\{\{).*$))") normrep = re.compile( r"(^.*?[^%\w]getelementptr )(((?:<\d* x )?)(.*?)(| addrspace\(\d\)) *\*(|>)(?:$| *(?:%|@|null|undef|blockaddress|getelementptr|addrspacecast|bitcast|inttoptr|\[\[[a-zA-Z]|\{\{).*$))") def conv(match, line): if not match: return line line = match.groups()[0] if len(match.groups()[5]) == 0: line += match.groups()[2] line += match.groups()[3] line += ", " line += match.groups()[1] line += "\n" return line for line in sys.stdin: if line.find("getelementptr ") == line.find("getelementptr inbounds"): if line.find("getelementptr inbounds") != line.find("getelementptr inbounds ("): line = conv(re.match(ibrep, line), line) elif line.find("getelementptr ") != line.find("getelementptr ("): line = conv(re.match(normrep, line), line) sys.stdout.write(line) apply.sh: for name in "$@" do python3 `dirname "$0"`/update.py < "$name" > "$name.tmp" && mv "$name.tmp" "$name" rm -f "$name.tmp" done The actual commands: From llvm/src: find test/ -name *.ll | xargs ./apply.sh From llvm/src/tools/clang: find test/ -name *.mm -o -name *.m -o -name *.cpp -o -name *.c | xargs -I '{}' ../../apply.sh "{}" From llvm/src/tools/polly: find test/ -name *.ll | xargs ./apply.sh After that, check-all (with llvm, clang, clang-tools-extra, lld, compiler-rt, and polly all checked out). The extra 'rm' in the apply.sh script is due to a few files in clang's test suite using interesting unicode stuff that my python script was throwing exceptions on. None of those files needed to be migrated, so it seemed sufficient to ignore those cases. Reviewers: rafael, dexonsmith, grosser Differential Revision: http://reviews.llvm.org/D7636 llvm-svn: 230786
2015-02-28 03:29:02 +08:00
%3 = getelementptr i32, i32* %d, i64 %2 ; <i32*> [#uses=1]
store i32 %1, i32* %3, align 4
%4 = add i8 %p.01, 1 ; <i8> [#uses=1]
%5 = add i32 %i.02, 1 ; <i32> [#uses=2]
br label %bb1
bb1: ; preds = %bb
%6 = icmp slt i32 %5, %n ; <i1> [#uses=1]
br i1 %6, label %bb, label %bb1.return_crit_edge
bb1.return_crit_edge: ; preds = %bb1
br label %return
return: ; preds = %bb1.return_crit_edge, %entry
ret void
}
; ScalarEvolution should be able to find the maximum tripcount
; of this multiple-exit loop, and if it doesn't know the exact
; count, it should say so.
; PR7845
; CHECK: Loop %for.cond: <multiple exits> Unpredictable backedge-taken count.
; CHECK: Loop %for.cond: max backedge-taken count is 5
@.str = private constant [4 x i8] c"%d\0A\00" ; <[4 x i8]*> [#uses=2]
define i32 @main() nounwind {
entry:
br label %for.cond
for.cond: ; preds = %for.inc, %entry
%g_4.0 = phi i32 [ 0, %entry ], [ %add, %for.inc ] ; <i32> [#uses=5]
%cmp = icmp slt i32 %g_4.0, 5 ; <i1> [#uses=1]
br i1 %cmp, label %for.body, label %for.end
for.body: ; preds = %for.cond
%conv = trunc i32 %g_4.0 to i16 ; <i16> [#uses=1]
%tobool.not = icmp eq i16 %conv, 0 ; <i1> [#uses=1]
%tobool3 = icmp ne i32 %g_4.0, 0 ; <i1> [#uses=1]
%or.cond = and i1 %tobool.not, %tobool3 ; <i1> [#uses=1]
br i1 %or.cond, label %for.end, label %for.inc
for.inc: ; preds = %for.body
%add = add nsw i32 %g_4.0, 1 ; <i32> [#uses=1]
br label %for.cond
for.end: ; preds = %for.body, %for.cond
[opaque pointer type] Add textual IR support for explicit type parameter to the call instruction See r230786 and r230794 for similar changes to gep and load respectively. Call is a bit different because it often doesn't have a single explicit type - usually the type is deduced from the arguments, and just the return type is explicit. In those cases there's no need to change the IR. When that's not the case, the IR usually contains the pointer type of the first operand - but since typed pointers are going away, that representation is insufficient so I'm just stripping the "pointerness" of the explicit type away. This does make the IR a bit weird - it /sort of/ reads like the type of the first operand: "call void () %x(" but %x is actually of type "void ()*" and will eventually be just of type "ptr". But this seems not too bad and I don't think it would benefit from repeating the type ("void (), void () * %x(" and then eventually "void (), ptr %x(") as has been done with gep and load. This also has a side benefit: since the explicit type is no longer a pointer, there's no ambiguity between an explicit type and a function that returns a function pointer. Previously this case needed an explicit type (eg: a function returning a void() function was written as "call void () () * @x(" rather than "call void () * @x(" because of the ambiguity between a function returning a pointer to a void() function and a function returning void). No ambiguity means even function pointer return types can just be written alone, without writing the whole function's type. This leaves /only/ the varargs case where the explicit type is required. Given the special type syntax in call instructions, the regex-fu used for migration was a bit more involved in its own unique way (as every one of these is) so here it is. Use it in conjunction with the apply.sh script and associated find/xargs commands I've provided in rr230786 to migrate your out of tree tests. Do let me know if any of this doesn't cover your cases & we can iterate on a more general script/regexes to help others with out of tree tests. About 9 test cases couldn't be automatically migrated - half of those were functions returning function pointers, where I just had to manually delete the function argument types now that we didn't need an explicit function type there. The other half were typedefs of function types used in calls - just had to manually drop the * from those. import fileinput import sys import re pat = re.compile(r'((?:=|:|^|\s)call\s(?:[^@]*?))(\s*$|\s*(?:(?:\[\[[a-zA-Z0-9_]+\]\]|[@%](?:(")?[\\\?@a-zA-Z0-9_.]*?(?(3)"|)|{{.*}}))(?:\(|$)|undef|inttoptr|bitcast|null|asm).*$)') addrspace_end = re.compile(r"addrspace\(\d+\)\s*\*$") func_end = re.compile("(?:void.*|\)\s*)\*$") def conv(match, line): if not match or re.search(addrspace_end, match.group(1)) or not re.search(func_end, match.group(1)): return line return line[:match.start()] + match.group(1)[:match.group(1).rfind('*')].rstrip() + match.group(2) + line[match.end():] for line in sys.stdin: sys.stdout.write(conv(re.search(pat, line), line)) llvm-svn: 235145
2015-04-17 07:24:18 +08:00
%call = call i32 (i8*, ...) @printf(i8* getelementptr inbounds ([4 x i8], [4 x i8]* @.str, i64 0, i64 0), i32 %g_4.0) nounwind ; <i32> [#uses=0]
ret i32 0
}
declare i32 @printf(i8*, ...)
define void @test(i8* %a, i32 %n) nounwind {
entry:
%cmp1 = icmp sgt i32 %n, 0
br i1 %cmp1, label %for.body.lr.ph, label %for.end
for.body.lr.ph: ; preds = %entry
%tmp = zext i32 %n to i64
br label %for.body
for.body: ; preds = %for.body, %for.body.lr.ph
%indvar = phi i64 [ %indvar.next, %for.body ], [ 0, %for.body.lr.ph ]
[opaque pointer type] Add textual IR support for explicit type parameter to getelementptr instruction One of several parallel first steps to remove the target type of pointers, replacing them with a single opaque pointer type. This adds an explicit type parameter to the gep instruction so that when the first parameter becomes an opaque pointer type, the type to gep through is still available to the instructions. * This doesn't modify gep operators, only instructions (operators will be handled separately) * Textual IR changes only. Bitcode (including upgrade) and changing the in-memory representation will be in separate changes. * geps of vectors are transformed as: getelementptr <4 x float*> %x, ... ->getelementptr float, <4 x float*> %x, ... Then, once the opaque pointer type is introduced, this will ultimately look like: getelementptr float, <4 x ptr> %x with the unambiguous interpretation that it is a vector of pointers to float. * address spaces remain on the pointer, not the type: getelementptr float addrspace(1)* %x ->getelementptr float, float addrspace(1)* %x Then, eventually: getelementptr float, ptr addrspace(1) %x Importantly, the massive amount of test case churn has been automated by same crappy python code. I had to manually update a few test cases that wouldn't fit the script's model (r228970,r229196,r229197,r229198). The python script just massages stdin and writes the result to stdout, I then wrapped that in a shell script to handle replacing files, then using the usual find+xargs to migrate all the files. update.py: import fileinput import sys import re ibrep = re.compile(r"(^.*?[^%\w]getelementptr inbounds )(((?:<\d* x )?)(.*?)(| addrspace\(\d\)) *\*(|>)(?:$| *(?:%|@|null|undef|blockaddress|getelementptr|addrspacecast|bitcast|inttoptr|\[\[[a-zA-Z]|\{\{).*$))") normrep = re.compile( r"(^.*?[^%\w]getelementptr )(((?:<\d* x )?)(.*?)(| addrspace\(\d\)) *\*(|>)(?:$| *(?:%|@|null|undef|blockaddress|getelementptr|addrspacecast|bitcast|inttoptr|\[\[[a-zA-Z]|\{\{).*$))") def conv(match, line): if not match: return line line = match.groups()[0] if len(match.groups()[5]) == 0: line += match.groups()[2] line += match.groups()[3] line += ", " line += match.groups()[1] line += "\n" return line for line in sys.stdin: if line.find("getelementptr ") == line.find("getelementptr inbounds"): if line.find("getelementptr inbounds") != line.find("getelementptr inbounds ("): line = conv(re.match(ibrep, line), line) elif line.find("getelementptr ") != line.find("getelementptr ("): line = conv(re.match(normrep, line), line) sys.stdout.write(line) apply.sh: for name in "$@" do python3 `dirname "$0"`/update.py < "$name" > "$name.tmp" && mv "$name.tmp" "$name" rm -f "$name.tmp" done The actual commands: From llvm/src: find test/ -name *.ll | xargs ./apply.sh From llvm/src/tools/clang: find test/ -name *.mm -o -name *.m -o -name *.cpp -o -name *.c | xargs -I '{}' ../../apply.sh "{}" From llvm/src/tools/polly: find test/ -name *.ll | xargs ./apply.sh After that, check-all (with llvm, clang, clang-tools-extra, lld, compiler-rt, and polly all checked out). The extra 'rm' in the apply.sh script is due to a few files in clang's test suite using interesting unicode stuff that my python script was throwing exceptions on. None of those files needed to be migrated, so it seemed sufficient to ignore those cases. Reviewers: rafael, dexonsmith, grosser Differential Revision: http://reviews.llvm.org/D7636 llvm-svn: 230786
2015-02-28 03:29:02 +08:00
%arrayidx = getelementptr i8, i8* %a, i64 %indvar
store i8 0, i8* %arrayidx, align 1
%indvar.next = add i64 %indvar, 1
%exitcond = icmp ne i64 %indvar.next, %tmp
br i1 %exitcond, label %for.body, label %for.cond.for.end_crit_edge
for.cond.for.end_crit_edge: ; preds = %for.body
br label %for.end
for.end: ; preds = %for.cond.for.end_crit_edge, %entry
ret void
}
; CHECK: Determining loop execution counts for: @test
; CHECK-NEXT: backedge-taken count is
; CHECK-NEXT: max backedge-taken count is -1
Fix a bug in SCEV's backedge taken count computation from my prior fix in Jan. This has to do with the trip count computation for loops with multiple exits, which is quite subtle. Most passes just ask for a single trip count number, so we must be conservative assuming any exit could be taken. Normally, we rely on the "exact" trip count, which was correctly given as "unknown". However, SCEV also gives a "max" back-edge taken count. The loops max BE taken count is conservatively a maximum over the max of each exit's non-exiting iterations count. Note that some exit tests can be skipped so the max loop back-edge taken count can actually exceed the max non-exiting iterations for some exits. However, when we know the loop *latch* cannot be skipped, we can directly use its max taken count disregarding other exits. I previously took the minimum here without checking whether the other exit could be skipped. The correct, and simpler thing to do here is just to directly use the loop latch's max non-exiting iterations as the loops max back-edge count. In the problematic test case, the first loop exit had a max of zero non-exiting iterations, but could be skipped. The loop latch was known not to be skipped but had max of one non-exiting iteration. We incorrectly claimed the loop back-edge could be taken zero times, when it is actually taken one time. Fixes Loop %for.body.i: <multiple exits> Unpredictable backedge-taken count. Loop %for.body.i: max backedge-taken count is 1. llvm-svn: 209358
2014-05-22 08:37:03 +08:00
; PR19799: Indvars miscompile due to an incorrect max backedge taken count from SCEV.
; CHECK-LABEL: @pr19799
; CHECK: Loop %for.body.i: <multiple exits> Unpredictable backedge-taken count.
Fix a bug in SCEV's backedge taken count computation from my prior fix in Jan. This has to do with the trip count computation for loops with multiple exits, which is quite subtle. Most passes just ask for a single trip count number, so we must be conservative assuming any exit could be taken. Normally, we rely on the "exact" trip count, which was correctly given as "unknown". However, SCEV also gives a "max" back-edge taken count. The loops max BE taken count is conservatively a maximum over the max of each exit's non-exiting iterations count. Note that some exit tests can be skipped so the max loop back-edge taken count can actually exceed the max non-exiting iterations for some exits. However, when we know the loop *latch* cannot be skipped, we can directly use its max taken count disregarding other exits. I previously took the minimum here without checking whether the other exit could be skipped. The correct, and simpler thing to do here is just to directly use the loop latch's max non-exiting iterations as the loops max back-edge count. In the problematic test case, the first loop exit had a max of zero non-exiting iterations, but could be skipped. The loop latch was known not to be skipped but had max of one non-exiting iteration. We incorrectly claimed the loop back-edge could be taken zero times, when it is actually taken one time. Fixes Loop %for.body.i: <multiple exits> Unpredictable backedge-taken count. Loop %for.body.i: max backedge-taken count is 1. llvm-svn: 209358
2014-05-22 08:37:03 +08:00
; CHECK: Loop %for.body.i: max backedge-taken count is 1
@a = common global i32 0, align 4
define i32 @pr19799() {
entry:
store i32 -1, i32* @a, align 4
br label %for.body.i
for.body.i: ; preds = %for.cond.i, %entry
%storemerge1.i = phi i32 [ -1, %entry ], [ %add.i.i, %for.cond.i ]
%tobool.i = icmp eq i32 %storemerge1.i, 0
%add.i.i = add nsw i32 %storemerge1.i, 2
br i1 %tobool.i, label %bar.exit, label %for.cond.i
for.cond.i: ; preds = %for.body.i
store i32 %add.i.i, i32* @a, align 4
%cmp.i = icmp slt i32 %storemerge1.i, 0
br i1 %cmp.i, label %for.body.i, label %bar.exit
bar.exit: ; preds = %for.cond.i, %for.body.i
ret i32 0
}
; PR18886: Indvars miscompile due to an incorrect max backedge taken count from SCEV.
; CHECK-LABEL: @pr18886
; CHECK: Loop %for.body: <multiple exits> Unpredictable backedge-taken count.
; CHECK: Loop %for.body: max backedge-taken count is 3
@aa = global i64 0, align 8
define i32 @pr18886() {
entry:
store i64 -21, i64* @aa, align 8
br label %for.body
for.body:
%storemerge1 = phi i64 [ -21, %entry ], [ %add, %for.cond ]
%tobool = icmp eq i64 %storemerge1, 0
%add = add nsw i64 %storemerge1, 8
br i1 %tobool, label %return, label %for.cond
for.cond:
store i64 %add, i64* @aa, align 8
%cmp = icmp slt i64 %add, 9
br i1 %cmp, label %for.body, label %return
return:
%retval.0 = phi i32 [ 1, %for.body ], [ 0, %for.cond ]
ret i32 %retval.0
}
; Here we have a must-exit loop latch that is not computable and a
; may-exit early exit that can only have one non-exiting iteration
; before the check is forever skipped.
;
; CHECK-LABEL: @cannot_compute_mustexit
; CHECK: Loop %for.body.i: <multiple exits> Unpredictable backedge-taken count.
; CHECK: Loop %for.body.i: Unpredictable max backedge-taken count.
@b = common global i32 0, align 4
define i32 @cannot_compute_mustexit() {
entry:
store i32 -1, i32* @a, align 4
br label %for.body.i
for.body.i: ; preds = %for.cond.i, %entry
%storemerge1.i = phi i32 [ -1, %entry ], [ %add.i.i, %for.cond.i ]
%tobool.i = icmp eq i32 %storemerge1.i, 0
%add.i.i = add nsw i32 %storemerge1.i, 2
br i1 %tobool.i, label %bar.exit, label %for.cond.i
for.cond.i: ; preds = %for.body.i
store i32 %add.i.i, i32* @a, align 4
%ld = load volatile i32, i32* @b
%cmp.i = icmp ne i32 %ld, 0
br i1 %cmp.i, label %for.body.i, label %bar.exit
bar.exit: ; preds = %for.cond.i, %for.body.i
ret i32 0
}
; This loop has two must-exits, both of which dominate the latch. The
; MaxBECount should be the minimum of them.
;
; CHECK-LABEL: @two_mustexit
; CHECK: Loop %for.body.i: <multiple exits> Unpredictable backedge-taken count.
; CHECK: Loop %for.body.i: max backedge-taken count is 1
define i32 @two_mustexit() {
entry:
store i32 -1, i32* @a, align 4
br label %for.body.i
for.body.i: ; preds = %for.cond.i, %entry
%storemerge1.i = phi i32 [ -1, %entry ], [ %add.i.i, %for.cond.i ]
%tobool.i = icmp sgt i32 %storemerge1.i, 0
%add.i.i = add nsw i32 %storemerge1.i, 2
br i1 %tobool.i, label %bar.exit, label %for.cond.i
for.cond.i: ; preds = %for.body.i
store i32 %add.i.i, i32* @a, align 4
%cmp.i = icmp slt i32 %storemerge1.i, 3
br i1 %cmp.i, label %for.body.i, label %bar.exit
bar.exit: ; preds = %for.cond.i, %for.body.i
ret i32 0
}
; CHECK-LABEL: @ne_max_trip_count_1
; CHECK: Loop %for.body: max backedge-taken count is 7
define i32 @ne_max_trip_count_1(i32 %n) {
entry:
%masked = and i32 %n, 7
br label %for.body
for.body:
%i = phi i32 [ 0, %entry ], [ %add, %for.body ]
%add = add nsw i32 %i, 1
%cmp = icmp ne i32 %i, %masked
br i1 %cmp, label %for.body, label %bar.exit
bar.exit:
ret i32 0
}
; CHECK-LABEL: @ne_max_trip_count_2
; CHECK: Loop %for.body: max backedge-taken count is -1
define i32 @ne_max_trip_count_2(i32 %n) {
entry:
%masked = and i32 %n, 7
br label %for.body
for.body:
%i = phi i32 [ 0, %entry ], [ %add, %for.body ]
%add = add nsw i32 %i, 1
%cmp = icmp ne i32 %add, %masked
br i1 %cmp, label %for.body, label %bar.exit
bar.exit:
ret i32 0
}
; CHECK-LABEL: @ne_max_trip_count_3
; CHECK: Loop %for.body: max backedge-taken count is 6
define i32 @ne_max_trip_count_3(i32 %n) {
entry:
%masked = and i32 %n, 7
%guard = icmp eq i32 %masked, 0
br i1 %guard, label %exit, label %for.preheader
for.preheader:
br label %for.body
for.body:
%i = phi i32 [ 0, %for.preheader ], [ %add, %for.body ]
%add = add nsw i32 %i, 1
%cmp = icmp ne i32 %add, %masked
br i1 %cmp, label %for.body, label %loop.exit
loop.exit:
br label %exit
exit:
ret i32 0
}
; CHECK-LABEL: @ne_max_trip_count_4
; CHECK: Loop %for.body: max backedge-taken count is -2
define i32 @ne_max_trip_count_4(i32 %n) {
entry:
%guard = icmp eq i32 %n, 0
br i1 %guard, label %exit, label %for.preheader
for.preheader:
br label %for.body
for.body:
%i = phi i32 [ 0, %for.preheader ], [ %add, %for.body ]
%add = add nsw i32 %i, 1
%cmp = icmp ne i32 %add, %n
br i1 %cmp, label %for.body, label %loop.exit
loop.exit:
br label %exit
exit:
ret i32 0
}